I’m interested in whether it’s possible to create categories, but with the ability to have several of them on the forum, as well as the ability to rename them.
This means that each category will have its own sections.
AI-generated summary
Creating multiple categories
Pirat wants to create multiple categories with their own sections, rather than subcategories within existing categories. He provided screenshots to illustrate the desired layout.
Moin asked for clarification on whether the question is about creating subcategories or their appearance in the sidebar. Pirat confirmed that he is referring to creating categories in general.
Jagster suggested that the issue might be related to the layout of the sidebar, specifically nesting categories under a header. Arkshine found a related discussion on meta, but no solution. JammyDodger pointed to the documentation on creating categories, but it does not address Pirat’s specific question.
We have quite a bit of the basics covered in our Documentation subcategories which may be worth a browse/search. Here’s the one for creating a category:
You misunderstood a little. I want to create not categories within, but a whole category itself with other categories inside.
This means that in the screenshot, I showed an open category. Now we need to create another category, Category 2, and if possible, change its name. 
Are you talking about the creating (sub-)categories in general or how (sub-)categories appear in the sidebar?
I can find a discussion about showing sub-categories in the sidebar (but no solution on what you want):
I have a feeling it is matter of layout of the sidebar. So nesting categories, that aren’t sub-categories, under some other category or header.