The concentration of a solution can be written in terms of the number of moles of the solute that are present in one liter of the solution. This is called the molar concentration or the molarity.
The volume of the solution is 660 mL and it has 33.4 g of aluminum acetate. The molar mass of aluminum acetate is 204 g/mol. 33.4 grams of aluminum acetate constitutes 33.4/204 moles = 0.1637 moles.
As 660 mL of the solution has 0.1637 moles, 1 liter of the solution will have 0.1637*(1000/660) = 0.2480 moles.
This gives the concentration of a solution with a volume of 660 mL that contains 33.4 grams of aluminum acetate as 0.2480 M