Not a dumb question! This first version is still mainly targetted at people who are in this area and generate some excitement, I do hope to make this more accesible though!

The inputs are 1. images 2. with a pose. The usual way to get poses for your images is https://github.com/colmap/colmap.

The output is a 3D model. Specifically a "Gaussian Splat", which is a sort of fuzzy point cloud. There are some tools out there to view & edit these (besides Brush), eg. https://playcanvas.com/supersplat/editor.