2HCL

mean 2 moles of HCL or 2 molecules of HCL?

if it is 2 moles,then is it means 2 * 6.022*10^23?

explain the difference between them

Actually when we write a balanced chemical equation of the type :

$2NaCl + H_{2}S{O}_4\to N{a}_{2}S{O}_4 + 2HCl$

In this equation if we consider coefficients to be molecules ,then it would depict that 2 molecules of NaCl produce 2 molecules of HCl.
In other case ,if we consider 2 moles of NaCl then it would mean that 2 moles of NaCl produce 2 moles of HCl

So we could consider coefficients either to be in moles or molecules.
But since 
Mole is a standard unit for the amount of substance. Therefore we prefer to write it as 2 moles of HCl.
Coefficients therefore represent moles of substance i.e reactant and products.


1 Mole contains = 6.023 x 10²³ molecules