The word keep has a variety of meanings.
To keep is to retain or preserve – I keep food fresh by keeping it in the fridge. Or it can mean detain or prevent – Don't let reading this blog keep you from writing. Or to guard or protect – keep yourself safe on the internet by keeping your passwords secret. It's also part of a castle!
There are other uses for the word, but I'm not going to keep on typing as that's kept me away from my stories long enough. Maybe some of you would like to keep on with the definitions or examples?