What does the Church teach about heaven?

Hi everyone. I’ve been thinking a lot about heaven lately, especially after a funeral in my family. I grew up Catholic but I realize I only have a vague idea: like “we’ll be with God,” but I don’t know what the Church actually teaches in a clear way.

What exactly is heaven according to Catholic teaching? Is it a place, a state, both? Do we recognize people we loved? What about the “new heavens and new earth” and our bodies after the resurrection—how does that fit with “going to heaven” right after death?

I’m not asking for private visions or scary end-times stuff—more like what the Bible and the Catechism really say, and how Catholics are supposed to live with hope instead of anxiety. Thank you.