Is loafs a plural noun or common noun?

The Word 'loafs' is not a noun. The Word 'loafs' is the third person, singular, present of the verb to loaf (to spend time idly).

Example: After finishing a chore, dad loafs on the patio sipping a beer.

The noun 'loaf' is a singular common noun. The plural common noun is loaves.

Example: While dad loafs on the patio, mom is baking two loaves of bread in the oven.