Espera is the present tense form of esperar for:
So by itself, espera could mean:
In this sentence, the subject is El señor, so it means the man/gentleman waits.
Yes. Esperar can mean:
In El señor espera aquí, the presence of aquí makes waits here the natural meaning.
Examples:
So context is what tells you which meaning is intended.
Spanish often does not need subject pronouns because the verb ending already gives information about the subject.
Here, though, the subject is stated as a noun phrase:
You do not need to add él because el señor already tells you who is doing the action.
Spanish normally would not say:
That would be wrong.
You could say:
But once you say el señor, the pronoun is unnecessary.
This is the most neutral Spanish word order:
So:
Spanish word order is more flexible than English, so you could also hear:
But El señor espera aquí is the plain, standard order.
Aquí has a written accent because Spanish spelling rules require it.
The stress falls on the last syllable:
Words ending in a vowel, n, or s normally stress the second-to-last syllable unless there is an accent mark. Since aquí is stressed on the last syllable, it needs the accent.
The accent mark here is mainly for:
It can mean different things depending on context.
Common uses of señor:
In El señor espera aquí, without a name, it often sounds like:
The exact English choice depends on the situation.
Yes. That is also correct.
There is a small difference:
In many everyday situations, both can translate naturally as The man is waiting here.
Spanish uses the simple present more often than English does, so espera can sometimes correspond to English is waiting.
It is fairly neutral and can sound polite because of señor.
So yes, it can sound polite or formal depending on context, especially if you are referring respectfully to an older man, a customer, or someone you do not know well.
In Spain, aquí is the normal choice for here.
Acá exists, but it is much more common in many Latin American varieties than in standard everyday Spain Spanish.
So for a learner focusing on Spain Spanish, aquí is the safest and most natural word to use here.