The gifts of the Holy Spirit are given to us particularly at confirmation. They are traditionally numbered as seven, coming from Isaiah 11. These are not tangible gifts or things like the sacraments which we can somehow see a cause. Rather, they are graces and spiritual gifts that help us to live better lives as Christians. They are called gifts of the Holy Spirit because the Holy Spirit is associated with the giving of grace.
Wisdom
Wisdom in the normal use of the term means having a lot of knowledge. If someone is wise, we say that they know much and know when to apply their knowledge to a particular situation. The gift of wisdom similarly gives us the ability to see things in their proper order and value. A person with this gift will see the true value of spiritual things over material things, and will see the world as God sees it. He will have a proper perspective on the importance or non-importance of all things, both spiritual and material, and be able to put each in its proper place. Of course this gift places a much higher emphasis on the things of God, since in the grand scheme of things God is far and away the most important thing in life. A person with wisdom loves the spiritual more than the physical, but also realizes that the latter has its proper place and values it accordingly.
Understanding
In the regular use of the word, understanding means grasping the meaning of the sentence. Similarly, the gift of the Holy Spirit that is Understanding helps us to know and comprehend the teaching of God, particularly through Jesus. His teachings were not always the easiest to understand or comprehend. Luckily, we have the Church to help us to interpret scripture and the teachings of Christ, but this gift of the Holy Spirit will also help us to take the teachings of Christ and the Church and apply it to our lives. There are some situations that crop up in everyday living in which it is not necessarily clear how we should act. This gift of the Holy Spirit helps us to discern exactly how to follow the will of God.
Counsel
This gift of the Holy Spirit has less to do with counsel as in advising and more with counsel as in decide the best course. It gives us the grace to make prudent decisions. There are many difficult situations in our lives which require us to both stand up for the truth and also do so in the most prudent way so that others will see the truth as well. When a person has this gift of the Holy Spirit, they are able to assess a situation and determine the best way that it can be resolved.
Fortitude
Fortitude gives us the courage to stand up for Jesus and follow Him, no matter what consequences come our way. Worldly courage means being able to bravely go into battle or fight in some way, without backing down. Spiritual fortitude is similar, but on a spiritual level. Sometimes this might mean not fighting physically, because that is not the most prudent thing to do at that time. Rather, it is the ability to see what must be done and then the courage to carry that out, even if it is difficult, humiliating or otherwise repulsive. It is very distinct from worldly courage, but it is based on the same principles and requires much more devotion and dedication. Only a person who is truly devoted to God will want to practice this gift of the Holy Spirit, because it can bring much suffering.
Knowledge
This gift of the Holy Spirit encourages each person to learn about God and to know the proper relationship between the spiritual and the physical. It is not nearly enough to just have a lot of book knowledge, and this is not even necessary. Rather, it helps us to understand God and see His plan for us and the world. When we understand what His plan is, even in an imperfect way, we can discern what we need to do in our lives. It gives us the ability to see our actions and the world in light of how they are in relation to God and the eternal realm. We see things in their reality, as opposed to how they may appear to those who can only see as far as this earth.
Piety
Piety is the gift of the Holy Spirit by which we demonstrate a great, burning love for God. Piety in its common usage can often be used derogatorily, to denote someone who looks like they love God but doesn't really. It can also be used to denote someone who follows all the rules of the Church. However, neither of these is authentic piety. Someone who is pious will follow the rules of the Church, but not because they are rules. Rather, they do so because that is what God wishes and they are in deep love with God. They don't care what anyone thinks about them; they want to do whatever will be pleasing to God. It stems from a desire deep within a person to please God in all things, not just so that person doesn't go to Hell, but because they really have a great love for God and could not imagine hurting Him in any way. Such a person recognizes that they owe everything in their life to God and they want to thank Him by loving and serving Him.
Fear of the Lord
Fear often has a negative connotation. People think of fear as having someone to be afraid of, who will punish them or otherwise negatively affect their lives. However, fear can have a positive meaning. You can be afraid of hurting someone else because of the harm they will suffer. A husband is fearful of doing something his wife doesn't like not because she is going to punish him in some way, but because he loves her and doesn't want her to be displeased. It is this second, more positive connotation of fear which “Fear of the Lord” implies. Those with this gift of the Holy Spirit do not want to offend God because of their great love for Him. They fear that they will commit some sin or fault which will displease God. Again, they aren't afraid that they will go to Hell, but rather are afraid of displeasing God because He is all good and perfectly worthy of our love. Anyone who truly loves God will not want to offend Him with sin, just as any person does not want to hurt someone they love. It is fear of offense, rather than fear of punishment, that this gift refers to.