terminal – How is coded in general?

So … I just found the terminal and thought about it: "What could I do with it?" Is there a command that lists many commands and their usage (like "help" in Windows cmd)? Can anyone in general give me a brief overview of the world of encoding with Mac?

Thank you for reading it when you answered, thank you even more!

PS. I know some commands on Windows, but not many. I have never coded with Mac unless we count a single code I found here system_profiler SPBluetoothDataType