56/71 as a percentage is 78.87%. This number tells you how large the fraction is when you compare it to a whole.
The fraction 56/71 is a bit less than 4/5, so it is close to 0.8 in decimal form. It is a common way to show a part of something when you have 56 out of 71 equal pieces.
When you see 78.87%, think of it as 78.87 parts out of every 100. It gives a quick sense of how big the fraction is without having to work with the denominator.
In everyday use, you might round it to 79% for a simple estimate, but the precise value stays at 78.87%.