Questions & Answers about O reboque chegou agora.
O is the masculine singular definite article, equivalent to the in English.
So o reboque = the tow truck / the trailer / the towing vehicle, depending on the meaning already given in context.
It tells you this is a specific, identifiable thing, not just any one.
- O reboque chegou agora. = The reboque arrived just now.
- Um reboque chegou agora. = A reboque arrived just now.
Because reboque is a masculine noun in Portuguese.
That means it normally takes masculine articles and adjectives:
- o reboque
- um reboque
- esse reboque
This grammatical gender is a property of the noun. It does not necessarily mean anything biological.