How do I make the player fall through without colliding?

Hello,

So, I want the player to fall through a platform without colliding with the floor, (for a smoother fall) how do I do it? (also the other yellow sprite should not fall)

Basically the problem is that instead of ignoring completly the platform it does a little stop before falling, and that should not happen

I also made a little video to explain better

A mega-ultra-hyper-super simple and easy solution. Check it out: fileport.io/vPVfFaEwNXga

Thank youuuuuu!! It works!, but can you explain what is happeing because i don't get it please