There are a lot of analogies but they all fail in some way. I think PBS Spacetime does the best in general, with good graphics to back up the words.

My layman's explanation is probably all stuff you've heard before. Massive objects "warp" spacetime and things that get stuck in those "wells" eventually fall to the bottom due to drag (from a variety of sources).

You've also probably seen the rubber sheet with a bowling ball in the middle used to represent that warping. To visualize that in 3D, I like to imagine a 3D grid of nodes and edges (like a jungle gym of joints and bars) where the whole thing is flexed inward towards a center point. More warped near the center, less warped further out. That kind of conveys the acceleration from gravity felt by things around that center mass.