You can make your computer do everything on its own, in other words, you can play your games and let the program modify the memory spaces of your choice without having to keep an eye on anything other than the game itself.
It was initially only conceived for Windows, but over time its developers decided to expand the compatible platforms and bring it over to Mac computers. Cheat Engine is a program that analyzes the content of your computer's memory whilst you're in a game to be able to modify its values.