noun which may take the genitive case particle 'no'
youngish; young-looking
Describes someone or something that appears somewhat young or youthful. Often used as a no-adjective modifying a noun.
彼は若めの服を着ている。
He is wearing youngish clothes.
若めの先生が担任になった。
A young-looking teacher became our homeroom teacher.
若い means 'young' as a plain adjective, while 若め is a no-adjective meaning 'youngish' or 'on the young side'.
Formed from 若い (young) + め (suffix indicating tendency or somewhat).