Do all squares have two pairs of parallel sides? Explan

Yes any square is also a parallelogram, but not the other way around (some parallelograms are not squares). In other words, any square is a parallelogram.

If you draw a Venn Diagram, the set of squares will be entirely inside the set of parallelograms.

This is because any rhombus is also a parallelogram, and the same applies to rectangles as well. A square is the combination of a rhombus and rectangle.

Rhombus = four sided figure where all sides are equal

Rectangle = four sided figure where all angles are equal to 90 degrees