A Mole is the mass of a substance containing the Avogadro Constant of particles. For example, 23g of sodium contain the Avogadro Constant of atoms, and the mass of this is 1 mole. 17g of ammonia contain the Avogadro Constant of NH3 molecules.
One Mole is the amount of any substance that contains as many particles as there are carbon atoms in 12 g of carbon-12. Some care is needed. 58.5 g of sodium chloride is the mass of one mole of this substance. However, it is ionic, and 1 mole consists of 1 mole of Na+ ions and 1 mole of Cl- ions. This is two moles of ions in total.
See also Avogadro Constant | Relative Atomic Mass | Relative Molecular Mass