In Mexico City, our Amigos D.F. return to tell us something about arquitectura (architecture) in el D.F. (in Mexico City, that is). Indicating a nearby building, we hear:
O sea, abajo es una zona comercial, todo lo que vendría a ser la planta baja... y arriba, allá, son este... departamentos residenciales.
I mean, below it's a commercial area, everything that would be the ground level... and above, there, are umm... residential apartments.
Captions 29-31, Amigos D.F. - ArquitecturaPlay Caption
Despite the rambling nature of this unscripted dialogue, it's easy enough to understand that there are commercial businesses on the ground floor of this building and residential apartments above. If the building has an elevator, pressing the p.b. (planta baja) button will take you to street level.
Push "1" in the same elevator and you'll end up on what's referred to as the "second floor" in New York or Miami. You see, in Spain and in Latin America, "el primer piso" is "the first floor *above* the ground level."
¿Dónde está ubicado el restaurante? -En el primer piso.
Where is the restaurant located? -On the first floor.
Captions 71-72, Cleer y Lida - Recepción de hotelPlay Caption
So, let's take this language lesson up a step. Say you want to visit your Mexican friend in his apartment up on "2." That's el segundo piso ("the second floor"). You see, you rarely hear la segunda planta or la primera planta outside of architectural drawings. In everyday speech, you'll usually hear pisos instead of plantas describe floors 1 through, well, the sky's the limit.
¿Ves ese edificio que esta ahí al frente? En el segundo piso, de ahí subís y ahí es tu salón.
Do you see that building that's over there in front? On the second floor, you go up there and there's your classroom.
Captions 48-49, La Sucursal del Cielo - Capítulo 1Play Caption
A final note on arquitectura: Departamento is the word of choice for Latin American apartments. Meanwhile, over in Spain, you'll typically hear apartamento.