What is meant by the ‘volume’ of an object?
The space occupied by the object
Volume is the quantity of three-dimensional space enclosed by some closed boundary, for example, the space that a substance (solid, liquid, gas, or plasma) or shape occupies or contains. The volume of an object is thus the space occupied by it.
We can look at it this way. Imagine there is small cupboard. I keep a large bag inside it. The space inside it is less. If I keep a small bag inside it, the space left in the cupboard is more. This means that the volume of the large bag is more.