It means put your answer in fraction form and reduce it to lowest terms.
Example.
If your answer was 9.6, then you need to put this into fraction form (this is expressing it as a fraction). Start with the .6 and make this 6/10. Now you have 9 and 6/10. Now put the 9 into the fraction as well. You should now have 96/10. The answer is now expressed as a fraction, but it needs to be simplified still. 48/5 is the fraction expressed in the lowest terms.
If you want to check your answer then just punch 48 / 5 = into the calculator and it will say 9.6. That is how you know your answer is correct.
Example.
If your answer was 9.6, then you need to put this into fraction form (this is expressing it as a fraction). Start with the .6 and make this 6/10. Now you have 9 and 6/10. Now put the 9 into the fraction as well. You should now have 96/10. The answer is now expressed as a fraction, but it needs to be simplified still. 48/5 is the fraction expressed in the lowest terms.
If you want to check your answer then just punch 48 / 5 = into the calculator and it will say 9.6. That is how you know your answer is correct.