The option and command keys are standard Mac keys. In general they require no explanation.
If you are coming from Windows PCs, then basically option is the alt key, and command is the Windows key. Control is the same as in any other keyboard.
What they do, depends on context, app, and what you are doing at the time. So there's no real unique explanation for them.
For instance, normal commands like copy, cut, paste, would be performed by holding down the command key plus the letters c , x, and v respectively.
Option works similarly, with other keys, and what it does depends on context.
See here more more keyboard options using those keys: Mac keyboard shortcuts - Apple Support
Note that not all keyboard shortcuts will work on an iPad.