1 - Uses a language without any knowledge of its idioms and conventions. As an example, writes Python code that looks like C or Java.
2 - Is aware of basic idioms taught in a tutorial. For Python, these would be using for ... in list rather than for i in range(len(list)), and other similar basic python constructs.
3 - Knowledge of community idioms and the standard library. with statements, using os.path for handling file paths are indications of this level.
4 - Adept of use of a language and its ecosystem found only after writing a lot of code with it.