Questions & Answers about El autobús para ahí.
Here, para is not the preposition for. It is the verb parar in the he/she/it form of the present tense.
So:
- para as a preposition = for, in order to, towards
- para as a verb form = stops
In El autobús para ahí, el autobús is the subject, so para is understood as stops.
Both are possible.
- El autobús para ahí = the bus stops there
- El autobús se para ahí = the bus stops there / comes to a stop there
In real Spanish, especially in everyday speech, parar and pararse can both be used in this kind of situation. Se para can sound a bit more like comes to a stop, but the sentence you were given is grammatical and natural.