Dear student,
The solution to your question is:
0.375 M aqueous solution of sodium acetate means that 1000 mL of solution containing 0.375 moles of sodium acetate.
Therefore Number of moles of sodium acetate in 500 mL=(0.375/1000)*500=0.375/2=0.1875
Molar mass of sodium acetate =82.0245 g per mol
so, mass of sodium acetate acquired =0.1875*82.0245 g= 15.380 grams
regards