I need help
What kind of a simple 2d game can I make on play canvas
Yes it is quite possible to make a 2d game in playcanvas, however the engine is primarily designed for 3d games and at the moment 2d tools are somewhat limited.
If you are looking for a simple game to make to learn, try making Pong, Space Invaders, Tetris, etc. They are good starting points. Pong especially if you have never made a complete game before.