71/78 as a percentage is 91.03%. This value tells you how large the fraction is compared to a whole, expressed in a way that’s easy to understand at a glance.
The fraction 71/78 can be thought of as 71 parts out of a total of 78 equal parts. When you look at it as a percent, it shows that the fraction is just a little under the whole, since it’s close to 100 %. This makes it useful for quick comparisons.
In everyday situations, you might see a similar percentage on a report card, a sports stat, or a sales figure. Knowing that 71/78 equals 91.03% helps you see that the result is very strong, but not perfect.