56/91 as a percentage is 61.54%. This is the rounded value you get when you change the fraction to a percent form.
The fraction 56/91 can be simplified to 8/13, which still represents the same part of a whole. Whether you write it as 56/91, 8/13, or 61.54%, the meaning stays the same: just over half of the whole.
Percentages like this are useful in everyday life—think of test scores, discounts, or statistics. Seeing the number as 61.54% makes it easy to compare with other percentages you might encounter.