Learn French: Allô, tu es là ? - Hello, are you there?

In French, Allô is used almost exclusively when greeting someone on the telephone. If you were greeting someone face-to-face, you would use Bonjour or Salut.

This is a question, but the words are in the normal statement order (tu es). Is that correct?

Yes! In everyday spoken French, it is very common to ask a question simply by using the normal subject-verb order and raising the pitch of your voice at the end. You could also say Est-ce que tu es là ?, but Tu es là ? is much more natural for a casual phone call.

Does là mean "here" or "there"?

It can mean both! While ici strictly means "here" and là often means "there", French speakers frequently use the phrase être là (to be there/here) to talk about someone's general presence. Depending on the context, tu es là ? translates to "are you there?" or "are you here?".

Why does the word là have an accent mark on the "a"?

The grave accent on là does not change how the word is pronounced, but it does change the meaning. It exists in writing just to distinguish the location word là (there) from the feminine word for "the", which is la.