Questions & Answers about São quatro e meia.
Why does the sentence start with São (they are) instead of É (it is)?
Why do we use the feminine meia instead of the masculine meio?
Can I add the word horas to this sentence?
Yes, you could completely correctly say São quatro horas e meia. However, just like in English, it is very common and natural to drop the word for "hours" when the context makes it obvious you are telling the time.
This lesson is teaching à and às. Why aren't we using às here?
The contraction às means "at the" and is used to say at what time an event happens (for example, "The class is at four" is A aula é às quatro). Because this sentence is just stating what the current time is right now, we only need the verb São, with no need for an "at" preposition.