The fraction 15/27 is equal to 55.56% when converted to a percentage. This means that if you had 27 items and took 15 of them, you'd have about 55.56% of the total. It's a bit more than half, so you can think of it as having a little over 5 and a half parts out of every 10.
In everyday life, you might see this percentage in various situations. For example, if a student got 15 questions right out of 27 on a quiz, their score would be 55.56%. Or if a basketball player made 15 out of 27 free throw attempts, their free throw percentage would be 55.56%. It's a useful fraction to know, especially when dealing with things that come in groups of 27.