A 6000 BTU air conditioner can cool a room that is about 150 to 250 square feet. If the room is a very sunny room then it would lean more towards the smaller end of the room size.
600 square feet.
275 square feet
Yes, a 4.5 ton air conditioner would be the minimum size for 2000 square feet.
A 15000 BTU air conditioner can cool an area of up to 750 square feet. Larger areas can be cooled but will be ineffective and put a strain on the unit.
Type in "6000 square feet in square meters" in Google search and you will get "6000 (square feet) = 557.41824 square meters".
It has a floor area of 6000 square feet.