28.00% is the percentage that corresponds to the fraction 28/100.
The fraction 28/100 simply means 28 parts out of a total of 100 equal parts. Because the denominator is already 100, the fraction can be read directly as a percent, showing how much of a whole it represents.
In everyday use, you might see 28.00% on a test score, a discount, or a statistic. It tells you that just a little over a quarter of the total is being described, making it easy to compare with other percentages.