The eyebrow term is making reference to a second navigation on top of the main navigation (that would be the eyes). So, the eyebrows would be something with less hierarchy than the main subject, but placed on top of the main subject.
What is an eyebrow on a website?
Overview: An eyebrow headline is 1-3 keywords or phrase placed above the headline. The goal of the eyebrow is to sum up the content in a few words to make it easier for a user to scan the page and find what they are looking for.
What is an eyebrow in ux?
Eyebrow text is a descriptive keyword or phrase placed above the main headline and blurb. It appears in a smaller font and sums up the content in just a few words.