Garlic is supposed to bring good luck to some people.
Garlic is not only supposed to bring good luck but garlic is also thought to banish sorcerers and evil spirits from a persons life.
I do not believe in those superstitions but some people do.
Garlic or anything else does not really bring any good luck.
But some people like to hang garlic around their neck or put garlic wherever they are so that they hopefully have good luck.
You're gonna have good luck, bad luck etc no matter what and whether you have garlic around you or not.