Translation:There are many galaxies in the universe.
Zonnestelsel - Solar system = A star and things (e.g. planets, asteroids, etc) that orbit it.
Sterrenstelsel - Star system (A term Duo still refuses to acknowledge, despite the fact that it's more accurate and the LITERAL translation) = A group of stars (some of which may be part of solar systems) that orbit each other.
Galaxy - a star system containing a large number of stars, sometimes called a star cluster.
As far as I can tell, in Dutch, there isn't any disambiguation between "star system" and "galaxy"... I suspect this is because most scientific papers by Dutch people would be written in English.