6/26 as a percentage is 23.08%. This number tells you how much of a whole the fraction represents when you look at it in terms of hundredths.
The fraction 6/26 can be reduced to 3/13, which is a simpler way to see the same value. Whether you write it as 6/26, 3/13, or 23.08%, the meaning stays the same.
Knowing the percentage makes it easy to compare this part to other percentages, like a test score or a discount. It shows that the part is just under a quarter of the whole.