"Spends time with" is a popular synonym for "hangs out with." It conveys the idea of socializing and enjoying someone's company in a non-committal way. Other synonyms that could be used include "chills with," "hobnobs with," "associates with," and "mixes with." Each of these phrases implies a level of casualness and camaraderie that is typically associated with socializing. Whether you're catching up with old friends or mingling with new acquaintances, these synonyms can help you convey the idea of spending time with others in a relaxed and comfortable way.