If you mean "convert 5 feet 3 inches to square meters" then it can't be done because 5 feet 3 inches is a measure of length (one-dimensional) and meters^2 is a measure of area (two-dimensional).
If you mean "take a square with sides equal to 5 feet 3 inches and convert the area of the square to square meters" then:
5 feet 3 inches
63 inches = one side
Area = side^2
Area = 63^2
Area = 3969 in^2
39.3701 in = 1 meter
1550.00477401 in^2 = 1 meter^2
3969 / 1550.00477401 = 2.56 (about)
Area = about 2.56 meters^2