Scripts in Second Life can be attached to any object in the world, or any object worn by an avatar, but not to an avatar itself.
Scripts can make an object move, listen, talk, operate as a vehicle or weapon, change colour, size or shape. Many of the objects you see around you have scripts attached to them to allow them to do something, or to allow you to interact with them. They allow simple prims to become chairs, or hot air balloons or vendors or any of the interactive elements you see around you in Second Life.
Scripting is harder to learn than basic object manipulation, but like any skill if you invest some time and effort you will soon be on the road to creating your own scripts.
Many groups offer scripting courses which teach you all the basics to get you started. It is not hard to learn, but it does require time and persistence to master. Try looking in the Events listing of Search to find a class at a time that suits you. A good resource for scripting is the official LSL wiki:
http://wiki.secondlife.com/wiki/LSL_Portal