tatami room; straw-matted room
A room with tatami flooring, typical of traditional Japanese architecture.
I relaxed in the tatami room at the inn.
和室 is a general term for a Japanese-style room, which typically has tatami, while 畳敷きの部屋 specifically emphasizes the tatami flooring.
Compound of 畳敷き (tatami-jiki, 'tatami flooring') + の (attributive particle) + 部屋 (heya, 'room').