4 square units.
The easiest way to find this is by looking at the triangle as if NL was the base. In this case PM would be the height. Since a triangle is the same shape even when we move it or rotate it, this is a common strategy to finding areas when the direction is tough for us.
Now that we have this we can measure the lengths of the base and height and use them in the triangle area formula.
Base = 4
Height = 2
Area of a triangle = 1/2bh
Area of a triangle = 1/2(4)(2)
Area of a triangle = 2(2)
Area of a triangle = 4