mean the world to (someone)
1. To be ardently loved by or exceptionally important to someone. My little daughter means the world to me—I would do absolutely anything for her. Our cats mean the world to my boyfriend—he's completely obsessed with them!
2. To be something for which someone is deeply grateful or appreciative. Thank you so much for taking care of my kids when I was in the hospital. It really means the world to me!
be/mean (ˌall) the ˈworld to somebody
be very important to somebody; be loved very much by somebody: Her job means the world to her.They’ve only got one child and he’s all the world to them.