Hi Kundan,

The Mole is the unit of measurement in International System Unit(SI) for amount of substance. 1 Mole is just a number whose value is equal to the Avagadro’s number i.e. 6.022 * 1023. So, when someone claims of a matter to be of 1 mole in quantity, that implies that the matter under consideration contains exactly 6.022 * 1023 number of particles (atoms, molecules, ions, electrons or any other elementary entities). Hope this helps.

All the best!!

For mole concept , you should refer NCERT book of chemistry . it give very elaborate way with discriptive. And op tandon as well.