Lua scripts let you extend the cheat in various ways and are a great way to automate parts of the cheat or just add that one useless feature you always wanted to have. All you need to get started is a text editor and a basic knowledge of the Lua language. If you made a lua script and would like to release it for other people to use, you can do that in the CS:GO Lua scripts subforum.
Lua scripts are stored in your CS:GO Folder and loaded using the Lua container in the MISC tab. If you're having trouble installing a script, refer to Using lua scripts