Entrada obviously means "entrance" or "entry" and can also refer to a "ticket" that allows you to enter a play or a concert, but in the legal Spanish of Spain, it has another meaning that can confuse you if you are unaware of it.
In Spain entrada also means "deposit" or "downpayment" on a house or condominium. Thus, for example, a sign that says Venta de pisos sin entrada is not an attempt to sell apartments without any entrance door, but instead means "apartments for sale: no downpayment required." Pagamos la entrada del piso doesn't mean "we paid to enter the apartment" but "we made the downpayment on the apartment."
In Mexico a downpayment is called an enganche. In Argentina they say seña: Pagamos la seña por el departamento in Buenos Aires is the same thing as saying pagamos la entrada del piso in Madrid.