愉 is built from the 忄 (heart (left)) and 俞 (hollow out (in 輸·愉)) components.
It belongs to a phonetic family with 輸, 諭, and 癒 — they share the 俞 component and the reading ユ.
A common word using 愉 is 愉快 (ゆかい), meaning “pleasant, happy”.
Don't confuse it with 諭, 輸, and 癒.