A Space can be divided into further Spaces. To do this, a so-called Sub-Space can be added to the Space.
To do so, click on + Group in the bottom left of the Space view.
Then select New Space to add a Sub-Space.
Enter a name for the Sub-Space. Confirm with Create.
The Space view with a Sub-Space looks as follows. Clicking on the Sub-Space displays the Sub-Space view. The back arrow takes you from the Sub-Space back to the parent Space.