Imagine you are a movie star for just 15 minutes. Those 15 minutes are supposed to be very special for you because it’s the time when everyone is looking at you and talking about you. This is what people call the “15 minutes of fame.”
It's like when your picture is shown on the school bulletin board because you won the Best Artist award or when you did a magic show in the playground and everyone was cheering for you.
But remember, it's just for 15 minutes, which means it's not going to last forever. This is why people say "make the most of your 15 minutes of fame." You should try to do something special or make it count so people remember you even after your 15 minutes of fame is up.