バースデー (bāsudē) means “birthday”

More examples

来週は母のバースデーです。rai shū wa haha no bā su dē de su

My mother's birthday is next week.

It treats the date of birth as a recurring personal milestone that is observed each year.

誕生日tanjōbi: The standard Japanese word for the yearly date on which a person was born.

人が生まれた日を毎年迎える記念の日。hito ga u ma re ta hi o mai toshi muka e ru ki nen no hi

バースデー (bāsudē) comes from the English compound birthday, which joins birth with day to name the day of a person's birth.

English speakers usually hear birthday as a neutral everyday word, whereas the katakana バースデー (bāsudē) can add a branded or celebratory tone in Japanese.