Texture Paint Only Working On Bottom of Mesh

This is really weird, and I have no idea why it is happening, but when I go into Texture Paint mode, and I try to paint the mesh (a flat plane), nothing happens, but when I go to the bottom of the mesh, and start painting, it works. It shows up on both sides, but only one side will allow me to paint it. What’s going on, and how do I fix it?

Go to edit mode and flip normals and it should work as expected.

so THAT’S what flip normals actually means… Boy, do I feel dumb now. Thank you.