The phrase "renta de basement" loosely translates to "rent the basement" or "basement for rent" in English. The phrase uses the Spanish noun for basement instead of the more narrowly defined noun, sotano, which refers specifically to basement apartments. However, the two nouns are interchangeable.
"Renta" refers to both the apartment being available and the quantity of money needed to occupy the space in the terms of the lease. Grammatically, the phrase should use "para alquilar" or "en alquiler" to express that the apartment is available for rent. The phrase additionally is referring to basement apartments as housing that is situated below ground level.