A logic gate is something which can be implemented to perform a logical operation on one or more binary inputs and produce a single binary output. (Read this Wikipedia article for a more thorough explanation.) It can be quite confusing for beginners, but this map is a helping tool as it includes 7 different puzzle levels which help you better understand logic gates.
How to play?
In each level there will be a brief explanation of the puzzle at hand. Your objective is the use the levers to solve the puzzle. If you succeed then you can access the next level.
It's great to learn this in case you want to improve your redstone skills.