Brazilians say this "tá" all the time, in different contexts, but if you don't have a good dictionary or grammar, you can't find what it means.
You're already familiar with the verb estar (if not, click here for more info). If we conjugate estar in "Presente do Indicativo, we have:
Eu estou
Tu estás
Você/Ele/Ela está
Nós estamos
Vocês estão
Eles/Elas estão.
This is how it works: remove the first syllable - es - and write the ending the way you would pronounce it:
Eu tô
Você tá*
Ele/Ela tá
Nós tamos
Vocês tão
Eles/Elas tão.
- Eu tô feliz. (estou - I'm happy)
- Eu tava na praia quando você ligou. (estava - I was at the beach when you called me)
- Ele tava em casa. (estava - He was at home)
- Se eu tivesse na escola, teria feito a prova. (estivesse - If I had been at school, I would have taken the test.)
We also use tá as a short way of saying está bem and it means OK, alright, I got it - either in a question or answer. And you may also hear ah, ta as "oh, now I understand", or if someone is being ironic "oh, really?", yeah, right.
If it's Internet language, some people may write without the accents: tah or ta.
- Me liga mais tarde, tá? ( Call me later, ok?)
- Faça os deveres antes de ver TV, tá? (Do your homework before watching TV, ok?)
- Ah, tá! Você tirou 10 na prova! (Oh, really? You aced the test?)
- Ah, tá, primeiro direita, depois esquerda. (Oh, I got it. First right, then left.)