plz xplain mole concept

Mole Concept: As group of 12 of anything is called dozen, similarly, 6.023 × 10²³ number of entities is called one mole. The entities may be atoms, molecules or any other particles.

Mole is also called Avogadro constant which is denoted by N_A. 

As per definition- One mole is the amount of a substance that contains as many particles or entities as there are atoms in exactly 12 g of the C-12 isotope.