I read this a few weeks ago, and it's sticking with me. I think about the characters often, and I really wish I'd have read it with a group so I could refer to it and not get weird faces pulled in return. Brit Bennett must be a very wise old soul in a young woman's body. (She was apparently 25 when this was written.)
The Mothers are the old church ladies in a California community. The action revolves around the church, specifically one family in the church. But while it's based in the church, this is a very secular novel without any religious zealotry directed toward the reader. (Some zealotry gets directed toward characters.) The Mothers represent missing mothers, mothers who can't fulfill their duties, mothers who are actually fathers, and many other mother figures in today's world.
It's a quiet story about loving people we aren't sure how to love, or how to show we love; about what happens when we can't, don't or won't talk our loved ones and instead keep secrets. It's a story about the fact that even when someone doesn't show you they love you in the way you might have hoped for or doesn't tell you everything, they may be the one to come through for you. Conversely, those who profess love may not be there when things get tough. It's about family and the ache that comes from missing family. It's an excellent story. Read it if you haven't.