How big is 4 square meters?

Answer 1

it can be a Square of 2x2 meters.

Or a rectangle of 1x4 meters.

or a line that's 0.1 m wide and 40 m long.

or a bunch of other shapes whose area ends up the same.

For the purpose of rough comparison, a yard is almost as long as a meter.

Answer 2

Assuming room height is 4 meters, then :

area of ceiling and walls = 50 x 4 + 2 x 50 x 4 + 2 x 4 x 4 = 200 +400 +32 = 632 square meters