Queen
Queen Consort
noun
When a king takes a princess for a wife, she becomes a queen.
王妃 is a word for the wife of a reigning king. She's a queen because of who she married, not because she has any power herself. The more technical term for that is queen consort.
This is a jukugo word that uses the on'yomi readings of the kanji. You should be able to read this on your own.
これは王妃の首飾りです。
This is the queen's necklace.
その車に乗っていたのは王妃でした。
The person in that car was the queen.
第三王妃は、内心では第一王妃にうんざりしていた。
The third queen was secretly fed up with the first queen.