Molarity is all about moles of solute, which in your case is sodium chloride, per liter of solution.
Simply put, a #"1-M"# solution will contain one mole of solute in one liter of solution.
In your case, a#"1-M"# sodium chloride solution will contain exactly one mole of sodium chloride in #"1 L"# of solution.
In order to determine how many grams of sodium chloride are equivalent to one mole of sodium chloride, you need to use the compound's molar mass.
The molar mass tells you exactly what you need to know - what the mass of one mole of a substance is. Sodium chloride has a molar mass of about #"58.4 g/mol"#.
This means that every mole of sodium chloride has a mass of #"58.4 g"#. Therefore, to get a #"1-M"# sodium chloride solution, weight out #"58.4 g"# of sodium chloride and make the volume of the solution equal to #"1 L"#.
SIDE NOTE If you go by the number of sig figs you have for the molarity and volume of the solution, the answer should be
#m_"NaCl" = "60 g"#