2 stroke engines use a crankcase to pressurize the air-fuel mixture before transfer to the cylinder. Unlike 4 stroke engines, they cannot be lubricated by oil contained in the crankcase and sump: lubricating oil would be swept up and burnt with the fuel.
The precise 2 stroke oil ratio depends on your manufacturer’s instructions, as each engine can have varied requirements. If you put too much oil, it can generate additional carbon build-up, making it difficult to start the engine.