还【hái】

还 says that something is continuing, or that there is more of it. It goes before the verb.

Still, as of now

还没 for not yet

The commonest use at this level. 还没 says something has not happened up to now, and leaves open that it will.

没 alone says it did not happen; 还没 says it has not happened yet.

Adding one more thing

Here 还 does what 也 does, with a sense of the list growing.

还 softening an assessment

In front of a positive adjective, 还 means "reasonably" rather than "still": 还可以, 还好, 还不错.