Hello!
To find the volume of one ice cube, you'll need to find the length, width, and height. In the question, it states that each cube is 5cm. So, 5cm will be the length, width, and height. So you'll need to multiply 5 three times (5*5*5) ---> (25*5) ---> (125).
The volume, V, of one ice cube is 125cm³
Now to find the total volume of all of the cubes, you'll need to multiply 125 by 12. After doing so, you'll get a volume of...
V=1500cm³
I hope this helps!