I can see everything in the overview, why?

In my overview I can basically see all of my entities

How do I get rid of all this stuff? Or better, how do I specify which ones I want to see?

Start configuring your user interface. Pretty much you are in auto add mode. Once you take control, things will no longer be automatically added.

Take a look at this page, specifically the video to learn how to adjust the interface.

Well, you seem to just have the default interface.
You can go to the developer tools page and set it to lovelace (instead of states)
This will put ui-lovelace.yaml in your config directory
You can add views (tabs) in it to create different pages and then different cards to those, only items you state will then be shown.

HA, beaten to it by Petro

That’s not correct. Those are lovelace climate controls that don’t exist in the old interface.

:man_cartwheeling: