what is compleanos?
It is both a singular and plural noun. mi cupleaños, not mis cumpleaños unless you are trying to say birthdays.
Hello Dalia: Welcome to the forum. Is it your birthday today?
If it is, Feliz cumpleanos, (I know that the n is supposed to have a thing over it but when I try to put one, someone logs me out.)
Feliz Cumpleanos (with a thing over the n) means: Happy Birthday!