As a Verb or Adjective:
1. To be what happens or is the case because it is part of the usual processes of life and has little or nothing to do with changes made by humans. English = (be) natural.
2. To be a part of someone's personality without them acting or changing themselves in any way. English = (be) natural.
3. To be usual and ordinary, and what people expect. English = (be) normal.
1. Used alone to show your strong agreement with what someone has said. You think this is something that everyone would know or agree with. English = 'Of course!', 'Naturally'