A triangle has $3$ sides.

A square has $4$ equal sides and $4$ equal corners.

A kite has $4$ sides. It has $2$ pairs of equal sides. The equal sides touch.

A rhombus has $4$ equal sides but does not have equal corners.

A trapezium has $4$ sides, $2$ of which are parallel and $2$ are not.

A parallelogram has $4$ sides. It has $2$ pairs of parallel sides.

An oval is round and curves inward everywhere.