A genie is a supernatural being from ancient stories that can grant wishes.
You might have seen a genie in movies or books - often it's a magical creature who lives in a lamp and can make your dreams come true. But if someone says "I'm like a genie for my friends, I always know the answer to their problems", they're not talking about a supernatural being at all. In this case, the word is used as a metaphor - just like how a genie grants wishes, this person seems to have the power to solve their friends' troubles.
A jinn, a being descended from the jann, normally invisible to the human eye, but who may also appear in animal or human form.
