It is a square or a rhombus
Assuming that each vertex is used to connect exactly two sides, all two-dimensional shapes will have the same number of sides as vertices. So a shape with 4 sides will have 4 vertices and a shape with 3 sides will have 3 vertices. Think of a square (4 sides, 4 vertices) and a triangle (3 sides, 3 vertices).
4 - Because there are four vertices's (corners) on a rectangular shape. This can be proven when the distance between diagonal vertices's are the same.
it is called a isosceles shape if iT only has 2 sides that have the same exact length
A kite or arrowhead.
A four-sided shape with only 2 sides the same length is called a rhombus.