means a binary star system where a planet orbits two suns instead of one, sometimes literally, sometimes just a metaphor for having too many things pulling at you.

from astronomically real, binary and multi-star systems are common in the galaxy, but the phrase got mythologized by star wars luke skywalker staring at tatooine's double sunset in 1977, instantly making 'growing up somewhere with two suns' shorthand for restlessness and destiny.