I have cheched the DevHub but it only shows the functions, not what they do (for most of them), are there other sources?
This page right here actually has an A-Z index of what all the Developer forum covers up, I guess. Roblox Engine API Reference | Documentation - Roblox Creator Hub
But if you are finding like functions for each and every thing, I don’t think you would be actually able to find it. There is information about what its supposed to do though, and the parameters it expects, if its a function.