Spinach is considered an uncountable noun because it refers to a mass of leaves rather than individual items. When discussing spinach, you generally wouldn't say "two spinaches" but rather "two bunches of spinach" or simply "spinach" in a general sense. It is treated as a substance rather than a discrete object.
Transport is both countable and uncountable as a noun.
countable
uncountable
Uncountable
uncountable
The gerund painting is a countable noun, as in "There are 12 paintings in this room."
few is countable
countable
Countable
The noun 'steel' is an uncountable (mass) noun, a word for a substance.
he asked me if the word fire wood countable or uncountable?
Pasta is a countable noun