Yes. A square is a rectangle with 4 equal sides. It's a special case of a rectangle.
A rectangle is a quadrilateral (closed shape with 4 straight sides and 4 corners) with 4 right angles.
So if we compare a square to this definition:
- A square is a quadrilateral
- A square also has 4 right angles
So basically a square is just a special rectangle where all 4 sides are equal.