his/her birthday
En su cumpleaños, tomé un tren a la ciudad en la cual él vivía.
On his birthday, I took a train to the city where he lived.
Tom le pidió perdón a su novia por haberse olvidado de su cumpleaños.
Tom apologized to his girlfriend for forgetting her birthday.
De lo único que ha hablado todo el día es de usted y de su cumpleaños.
All he's talked about all day is you and your birthday.
— “Cumbres Borrascosas” (2026)
Is it their birthday today?
How was your birthday?
His birthday falls on a Sunday.
¿Por qué hablas así en su cumpleaños?
Why are you talking like that on his birthday?
— Ne Zha (2019)