Can the product be called "vinegar"?
0.125M of $\ce {Ba(OH)2}$ means 0.125 moles of $\ce {Ba(OH)2}$ per volume unit (so far I've only seen liters been used as volume unit) . 
Assuming that all the $\ce {Ba(OH)2}$ you used was consume on the reaction with the acetic acid, and knowing the ratio of $\ce {Ba(OH)2}$ and acetic acid on the reaction is 1/2 you`d have this reaction:

$$\ce {Ba(OH)2 + 2CH3CO-OH -&gt; Ba(CH3COO)2 + 2H2O}$$

All you need to do is calculate the amount of acetic acid consumed. Knowing the amount of acetic acid consumed based on the amount of moles of $\ce {Ba(OH)2}$ that are present on 37.5mL. Then you need to get the molar mass of acetic acid  and calculate the amount of mass of acetic acid you had. Then divide the total mass of vinegar by the mass of acetic acid  you found, multiply it by 100 and you'll have the mass percentage of acetic acid.