Leviticus 22:12 Commentary: Rashi, Or HaChaim, Siftei Chakhamim & Chizkuni

לאיש זר TO A LAYMAN — to a Levite or an ordinary Israelite (i. e. to any non-priest) (Sifra, Emor, Section 5 7).

ובת כהן כי תהיה לאיש זר, "And the daughter of a priest who marries an non-priest," etc. Torat Kohanim uses the restrictive word היא, "she," to exclude her mother, meaning her mother (the wife of a priest) may eat תרומה even though her daughter is not allowed to do so even if the mother had meanwhile become a widow (who had not remarried).

To a Levite or an Israelite. Rashi is answering the [following] question: that It is obvious that she has to marry an איש זר (lit. a nonrelative), because she is forbidden to relatives. He answers that regarding her, a Levite or an Israelite are considered a זר. [See Re’m]