What does "sleeping through the night" mean?

I constantly heard parents and medical professionals talk about their young babies (few weeks or months old) sleeping through the night but at the same time they still need to feed every 2-4 hours. Does sleeping through the nights mean literally they don't feed at night or just mean they do stir from sleep and feed without fully waking up over night? If the former, how can they not feel hungry at night? If the latter, dont all newborns sleep through the night from the beginning. My newborn (10 weeks now) for the first few weeks barely opened her eyes throughout the day and night even when feeding. Now she does wake up with her eyes open and active during the day and nurses every 2-4 hours at night depending on how much milk she managed to get into her body while feeding with her eyes close throughout the night. Just don't know if she is supposed to not feed as frequent like that, aka sleep through the night, at this point? And how all of the sudden the milk demand changes at night versus day?