Hi Crishan, The Avogadro Number (AN) is a two-sided concept.
In general, the AN is approximately 6.02 X 10^23 formula units per mole.
In specific cases, the AN has units of grams per mole.
Example: Ordinary atmospheric oxygen (O2) has a gram-molecular weight of 32 grams per mole. Why? Because the Avogadro Number of oxygen atoms has a mass of 16 grams. (Looking at the Periodic Table, the atomic weight of oxygen is 16.) An Avogadro Number of O2 molecules should have double that mass.