Question

4 equal sides and 4 square corners

Explanation:

A square is a quadrilateral with 4 equal sides and 4 right - angled (square) corners. Among the given shapes, the purple, pink, green and red (diamond - shaped) figures are squares (the red rectangle has 4 square corners but not 4 equal sides, and the turquoise shape is a parallelogram which does not have 4 square corners).

Answer:

The purple, pink, green and red (diamond - shaped) shapes.