Salut Olivia,
"la-bas" is an adverb and it means over there:
ce livre la-bas = that book over there or (there).
" la" is also an adverb and could have different meanings according to the context :
- it means "here", when indicating the position of the speaker:
viens la = come here!.
Est-ce que Olivia est la ? ( if Olivia is in the same room as speaker) = Is Olivia here?
- on the other hand it could mean "there" when indicating distance from speaker:
Est-ce que Olivia est la? ( asking on telephone for her)= Is Olivia there?
-It could also mean "this, these" or "that, those " :
ce livre la (with proximity to speaker ) = this book.
ce livre la ( with distance from speaker) = that book.
In other contexts it could mean :
-a partir de la = from then on.
-jusque la = until then.
-a quelques jours de la =a few days later.
Est en fin on peut user " la" aussi comme une exclamation " Oh ,la la! " et ca veut dire" oh my goodness!"