Gitel is Yiddish.
Tzadik is technically a correct answe, but it carries a religious context (more of a "good jew" than a good person)
There are many possible translations depending on the context. a few are:
Ish tov / Isha tova - Good man/woman (adjectives receive gender too!)
Adam tov - Good person ("adam" is male but can serve as an unspecific catch-all, not unlike "person")
Osseh tov - doer of good, literally.
Nadiv / Nedivah (m/f) - generous, also the closest word to "benevolent" in Hebrew
Shokher tov - good willing (archaic)