Formal:
* Mae'n hapus: This is the most literal translation, using the verb "mae" (is) and the adjective "hapus" (happy).
* Mae hi'n hapus: If you are referring to a female, you would use "hi" (she) instead of "n".
* Mae e'n hapus: If you are referring to a male, you would use "e" (he) instead of "n".
Informal:
* Hapus yw e/hi: This uses the adjective "hapus" followed by "yw" (is) and then the pronoun.
* Mae'n bleser iddo/iddi: This literally means "It is a pleasure for him/her", and is a more idiomatic way of saying "he/she is happy".
Examples:
* Mae'n hapus i weld ti. (He/She is happy to see you.)
* Hapus yw hi am ei gyflwyniad newydd. (She is happy about her new job.)
* Mae'n bleser iddo gael bod yn yma. (He is happy to be here.)
The best way to choose the right expression depends on the formality of the situation and who you are speaking to.