A relative pronoun acts as a conjunction and a pronoun.
e.g.: This is a book and it (the book) includes mathematical proof.
=>This is a book which includes mathematical proof. (The “which” acts as “and ” + “it”.)
関係代名詞は接続詞＋代名詞の働きをする.
例：This is a book and it (the book) includes mathematical proof.
=>This is a book which includes mathematical proof. (「which」は「and」と「it」の両方の働きをする.)
