Sodium chloride, also known as table salt, is an ionic compound composed of sodium cations $$Na^+$$, and chloride anions $$Cl^-$$ that has the formula unit $$NaCl$$.
You know that sodium chloride's formula unit contains
$$\bullet $$ one sodium atom
$$\bullet $$ one chlorine atom
This means that sodium chloride's molar mass will be the sum of the molar masses of those two atoms.
$$M_{MNaCl}=M_{Na}+M_{Cl}$$
A quick look in the periodic table and you'll see that the molar masses of sodium and chlorine, respectively are:
$$\bullet Na\to 22.989770\ g/mol$$
$$\bullet Cl\to 35.453\ g/mol$$
Therefore, the molar masses of sodium chloride will be:
$$M_{NaCl} =22.989770\ g/mol+35.453\ g/mol =58.44277\ g/mol$$
The molar mass of NaCl is $$58.44\ g/mol$$.