Both numbers (9.00 and 4.25) have three sig-figs. This means that the final answer will have three sig-figs as well.
Multiply the numbers to get: 9.00*4.25 = 38.25 which rounds to 38.3 because the answer must have three sig-figs.
The units will be "square inches" or "inches^2" or "in^2". There are various ways to write the units portion.
Overall, the final answer is 38.3 square inches.