counter
counter for beds
Used to count beds, futons, or hospital beds. Often appears in medical or lodging contexts.
この病院には100床のベッドがあります。
This hospital has 100 beds.
旅館の予約は3床お願いします。
Please reserve three beds at the inn.
台 is a general counter for machines and furniture, while 床 is specifically for beds.
From Middle Chinese 牀 (dzrjang, 'bed'). The kanji 床 is a variant used in Japanese for 'bed' or 'floor', and here it serves as a counter for beds.