Anyone know what "undervalued" means?

This listing is close to my dream listing since it's in my small-studio market - the only thing I could hope to afford in manhattan - but that window on the side looks like there is just enough space to place a bed next to it and build a makeshift wall to have a separate bedroom area. Too bad they don't accept dogs. I don't have a dog now but would prefer the option in the future if I am a homeowner. Interesting that the listing refers to the building as "undervalued". Anyone know what that means in general and/or do you know anything specifically about this building? Red flag? https://streeteasy.com/building/321-east-45-street-new_york/8h 321 East 45th Street #8H