Your skills are what define your character class and allow you to do the things that you do in the game. There are 27 skills in Morrowind, each falling under the category of Combat, Magic or Stealth. The following links will open a new window with a description of each skill (liberally copied from the game documentation), which actions will increase that skill and by how much (liberally copied from the Construction Set).
Remember that the point values are base values and can be significantly higher depending on whether the skill is Major, Minor or Miscellaneous and where you have chosen to specialize.