A rectangle is a 4-sided flat shape made of straight sides, where all four of it's interior angles are 90°.
From these simple facts, it is not hard to work out these related facts:
Opposite sides are parallel.
The sides with a single arrow are parallel to each other.
The sides with double arrows are parallel to each other.
Opposite sides are equal.
The sides with a single dash are equal in length to each other.
The sides with a double dash are equal in length to each other.
There are 2 lines of symmetry.