Being in someone's "good graces" means that that person is not angry or upset at you.
Most often, people try to "get in the good graces" of someone like:
- their boss
- their wife
- a king or queen
You can also use the phrase "get back in ___'s good graces" to talk about getting someone who's angry to stop being angry:
I need to do something to get back in my mother-in-law's good graces.