Ask HN: As a YC employee, what is the "equity in YC" benefit?

I saw this job posting for the Product Engineer, Work at a Startup:

https://www.workatastartup.com/jobs/41302

It says "We also offer highly competitive compensation, including equity in YC". What is equity in YC? Stock options, implying that YC could go public or get acquired? Profit sharing? I'm curious how one can value this equity, and how that potentially translates into cash in the bank now or later.