What does   3D game using 2D   images mean  ?   is it something like Baldi's basics?

I imagine something like classic 2.5D shooters like Doom or Wolfenstein 3D. I don't know Baldi's basics but it looks like it does the same, where things are sprites instead of full 3d models

Like u made a 3d game and all the textures and stuff...get the point...

Sorry i also dont know much :p

pretty sure it means just making an ordinary 3d game but without meshes,models and stuff,2d textures are like wall textures without 3d effect on them

plain .pngs

I thought of someting like Paper Mario ! Does it work ?

See for example this blogpost series about creating 2.5D racing game (similar style to old consoles in cinemas and other places).

I think they mean like this https://itch.io/jam/paint-jam-2019/rate/371820 or like other have said paper mario, Duke Nukem, Doom etc

In my opinion Baldi’s basics is the opposite of what they said, but really its just about having fun so dont worry to much about it.

literally whatever way you wanna implement paint drawings into 3d counts afaik