How can I make some room with my mac?

If I go in the apple menu (upper left corner) and I click on 'about this mac' item. I get this window (in the screenshot):

As you can see, there is the 'Apps' folder in red, the 'System' folder in light grey and another folder in dark grey which is the 'Autre' folder (not appearing in the screenshot, I have to hover my mouse over it to see its name. "Autre" in French means "Other" in english). This last one is taking a huge part of my disk: 35G bytes.

I'd like to make some room, and the disk utility on the right (the "Gérer" button, likely "manage" in english) does not help with that part. Here is another screenshot when I click on this button:

As you can see the "Autre" part ("Other" in english) is greyed and unclickable while it takes the most part: nearly 36Gbytes.

Will this button clickable in a futur version of macos?

What does it correspond to?

How can I make room on my mac? (knowing that I already made a lot of room with others folders, like the "Apps" folders and so on).