BGP filters question

Hello I want to know why in my import filter I need to allow 0.0.0.0/0 to receive all route from my upstream like this

Your question not clear.

Hello I rephrase, I am a basic Juniper user when I create my BGP filters I choose everything I want to drop in import.
Then everything else is allowed
Here I created my eBGP filter that blocks all private network when I apply it to my upstream I receive nothing I had to add 0.0.0.0/0 accept in my filter to receive routes from my upstream is this normal ?

You can use action ‘permit’ in prefixes, I think it will be more clear
And action ‘deny’ for route-maps for “bogons” prefixes.