how can google.com put a tab focus on an element that is not focusable

Please go to google.com and search for ‘dictionary’, navigate through tab key and select “skip to main content”:

step1

After hitting enter, the dictionary element gets focused:

step2

When I inspect it, it’s a div with a aria-level attribute with no tabindex.

step3

So my question is how can a non-focusable element gets focused like that?