This is the 977th most frequent Spanish word.
piso
"Floor" (of a building or room); "apartment" (in some regions).
Here, 'piso' refers to the floor of a room or building.
El piso de mi casa es de madera.
The floor of my house is made of wood.
In this context, 'piso' describes a level or story in a multi-story building.
Vivo en el quinto piso del edificio.
I live on the fifth floor of the building.
Here, 'piso' is used to mean an apartment or flat, especially in certain Spanish-speaking countries.