counter
counter for chairs or seats
Used to count chairs, seats, and similar items with legs. Not a general counter for furniture.
この部屋には椅子が四脚あります。
There are four chairs in this room.
noun
Refers to the foot or leg, often in a more formal or technical context compared to あし. Commonly used in compound words.
この机の脚は金属でできている。
The legs of this desk are made of metal.
足 is the common word for foot or leg in everyday language. 脚 is more formal or technical, and also used as a counter for chairs.
The kanji 脚 originally depicts a leg and is used in Chinese-derived compounds. The reading きゃく is the on'yomi.