How to get items out of a section depending on the branch?

Question

1C-Bitrix

The question is:
How to display the elements from the section that was clicked, depending on the branch that was selected?
I display categories using category.section.list, when switching, a list of all categories and one open element
opens. When the page is opened, a window should pop up where there are 3 branches, when a branch is selected, all elements belonging to this branch are shown, how can this be implemented?
As I understand it, you need to create a property on the element, and select the branches in which it will be, but I don’t know how to display it depending on this property ..