"Mi casa tiene un sótano."
Translation:My house has a basement.
Cellar should also be acceptable. Although Mavry points out that cellar and basement are differentiated in the dictionary, in day to day use they're completely interchangeable. I think which is more popular varies with region.
I have two versions of the Wizard of Oz in Spanish. One calls the cellar "sótano" and the other "gruta" (cave).
In English, I tend to think of a basement as being accessible from inside the house, but a cellar is accessed from outside the house. However, as you mentioned usage is probably regional.
In any case, hopefully both are accepted by now.
Does anyone know the origin of the word sótano? The spell is so different from basement/cellar that I can't remember.
I thought of French "souterrain" (=belowground). I think you can say "subterranean" in English, too.