Give a brief explanation on mole concept expert please

Mole is the SI unit for amount of substance. It is used for the measurement of very small, microscopic particles such as atoms and molecules. Broadly speaking, it is used to measure the number of particles whether atoms or molecules, present in a given amount of substance. One mole is the amount of substance that contains as many particles as there are atoms present in exactly 12g of ¹²C isotope of Carbon. It has been found that there are 6.022*10²³ atoms present in 12 g of¹²C isotope of Carbon.

1. One mole of any substance will always contain 6.023*10²³particles, no matter what the substance is. Therefore 1 mole of Na atoms contains 6.022 X 10²³atoms of Na, 1 mole of Hydrogen atom contains 6.022 X 10²³atoms of Hydrogen, 1 mole of Hydrogen molecule will contain 6.022 X 10²³ Hydrogen molecule (H₂), 1 mole of CO₂will contain 6.022 X 10²³molecules of CO₂.
2. One mole of any substance is always equal to its molar mass. We know that the molar mass of a substance is numerically equal to the atomic mass (for atoms) or molecular mass (for molecules) and is reported in grams. Therefore 1 mole of Na atoms = molar mass of Na atoms = 23 g.

1 mole of H₂O molecules = molar mass of H₂O molecules = 18.02 g
Let us solve a simple numerical to understand this concept in a better way.
Numerical:
Calculate the number of particles in each of the 46 g of Na atoms.
Solution:
In this numerical, it is desired to find the number of particles in 46 gm of Na.
We know that one mole of Na contains 6.023 × 10²³ particles.
Therefore, we will first find the number of moles in 46 gm of Na.
Number of moles of sodium = given mass / molar mass of sodium = 46/23 = 2 moles 

We know that 1 mole = 6.022 × 10²³ particles.
Therefore, 2 moles = 2×6.022 × 10²³ particles
  = 12.044 × 10²³ particles
Hence, 46 gm of Na contains 12.044 × 10²³ particles.