These measurements are based on a time, which is why we use 'minutes' and 'seconds', but to avoid confusion with real time measurement we put the word 'arc' in front to remind us we are dealing with arcs. So you can say, 'Those two stars are 4 degrees, or 240 arcminutes, or 14,400 arcseconds apart on the sky'. The sky is 360 degrees around.
Area is measured in square units, like a floor area is measured in square meters.
There are over 40 thousand square degrees in the sky. The sky is pretty big. For comparison, the Moon is only a half degree across. That gives it an area of only 0.2 square degrees. Next week, we'll see how the stars are distributed across the sky, using the numbers we just derived.