A Safe Space is a clearly defined area of segregation which is usually set up to protect the good people from those disgusting straight white males. In the Neckbeards universe, safe spaces are hazardous to protagonists while providing healing effects for any antagonists that pass over them. You're wise to avoid these areas which are clearly marked with the color pink. Stay out of it, cis-male scum!
While usually static in nature, Neckbeards: Basement Arena has some mobile varieties of safe spaces in the later basements.