Learn Hardcore Spanish (Spain): En ese banco cobran una comisión si haces la transferencia en ventanilla. - At that bank they charge a fee if you make the transfer at the counter.

In Spanish, it’s very common to use the 3rd person plural (cobran, dicen, hacen) with an unspecified subject to mean “they / people / the staff”. Here it effectively means the bank (staff) charges a fee, without explicitly repeating el banco as the grammatical subject.

What does cobrar mean here, and how is it different from pagar?

Cobrar = to charge / to collect (money) (from someone).
Pagar = to pay (money to someone).
So cobran una comisión means they charge a fee (you are the one who ends up paying it).

Why is it una comisión and not la comisión?

Una comisión introduces it as “a fee” in a general sense (one of the bank’s fees). If you were talking about a specific, already-known fee, you might see la comisión. In many real contexts, both can appear, but una is very natural for stating a policy: “they charge a fee if…”.

What does comisión mean in banking Spanish (Spain)?