Are these countable nouns

Arm is countable, for example: hold sb in arms, back and neck are countable, but not common,

The difference between cloth as a noun and uncountable noun

Cloth is usually uncountable
When it is countable, it refers to a table cloth for special purpose
I don't know how to ask. If I can help you, please accept it in time. Thank you!

Excuse me, cloth is an uncountable noun, right? Then why use a to cover the cut with a clean cloth

A piece / strip of cloth cover the cut with a clean cloth (as a bandage)

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