Translation:Two buses just arrived at the bus station.
Yes. Acabar de + verb = (have) just + verb. Ela acabou de sair = she (has) just left.
It rejected "two buses just arrived at the station". Yes, I know that this sentence is ambiguous and it could refer to a train station. But still, that's pretty picky.
When you have a word that ends with an S (not oxytones), the plural is the same
O ônibus = os ônibus
O lápis = os lápis
O tênis = os tênis
but the "oxítonas' ( oxytones) have plural: inglês = ingleses; país = países; revés = reveses.
Rodoviária is a bus station like where you get a bus to go long distances or transfer from the subway to a bus. Ponto de ônibus is a bus stop like where you wait on the street for the bus to pick you up.