Breakdown of Mis primos van a celebrar su cumpleaños aquí.
aquí
here
el primo
the male cousin
mi
my
su
his/her/its/their/your (formal)
Questions & Answers about Mis primos van a celebrar su cumpleaños aquí.
Why is the word a needed in van a celebrar?
In Spanish, to say you are going to do something in the near future, you use a conjugated form of the verb ir (to go) plus a plus an infinitive verb (the unconjugated action word). Here, van means they are going, so van a celebrar translates perfectly to they are going to celebrate. You cannot leave out the a!
Why is it su cumpleaños instead of sus cumpleaños since there are multiple cousins?
In Spanish, possessive adjectives like su (their) change to match the thing being owned, not the owners. Since the cousins are celebrating one shared event (a single birthday party), the word cumpleaños is treated as singular here, so we use the singular su.
Wait, doesn't cumpleaños end in an s? Doesn't that make it plural?
Not necessarily! Cumpleaños is a compound word made of cumple (completes) and años (years). Because of this, the word for birthday always ends in 's', even when we are only talking about one single birthday.
Why is it Mis primos and not Mi primos?