18 hours of the day not eating, 6 eating. It's usually called time restricted eating/feeding or an eating window with the idea being you'd do it every day. This is in contrast to extended/prolonged fasting, which is typically 24hr+.

In general IF (intermittent fasting) is a catch-all phrase, and not a particularly helpful one.

I try to focus eating during a 6 hour window. I'm not overly strict with myself. Sometimes it ends up 16/8, but on average I'm likely right around 18/6. So I eat most weekdays between 1:00P and 7:00P.