Mole is a unit of measurement used in determining the amount of any atoms, molecules or compounds. 1 Mole of any substance has a specific molar mass. For example, we have 1 mole of water (H2O) is equal to 18 grams of water.
1 mole water x (18 grams/mole) = 18 grams H2O
18 grams/mole is the molar mass of water.
Another example, 2 moles of NaCl has a mass of 116.88 grams.
2 moles NaCl x (58.44 grams/mole) = 116.88 grams NaCl
58.44 grams/mole is the molar mass of NaCl (Sodium chloride)