Gram atomic mass:

Atomic mass of an element expressed in grams is called gram atomic mass.

Gram atoms mass of an element contains 1 mole of atoms.

Examples:

Atomic mass of C = 12 amu                  $\therefore$ gram atomic mass of C=12 g

Atomic mass of Na = 23 amu                $\therefore$ gram atomic mass of Na = 23 g

Atomic mass of Zn = 63.54 amu           $\therefore$ gram atomic mass of Zn = 63.54 g