Quinto, a (os, as)
The 5th largest Spanish speaking country is the United States.
No, "La Quinta Estación" is a Spanish band's name. "La quinta estación" translates to "the fifth station" or "the fifth season" depending on the context.
Cinco de Febrero
Cinco de marzo.
El día jueves
You can say "el cinco de octubre". Not that month names are not capitalized in Spanish.
day 5 or the fifth day in spanish
tercer piso
if you mean spanish its "noveinty cinqo"
25 (veinticinco) de agosto
5a is the spanish abbreviation for "quinta" (Like us writing 5th for fifth) and estacion is station. The fifth station
It should be "quinta hora", since "hora" is feminine. It means "the fifth hour" or in some contexts, "the fifth period".