Translation:With this you can see stars and dreams.
"Herewith" is a little bit old-fashioned. You might still see it in formal correspondence (especially legal) - usually referring to something that is attached/included. E.g. "I enclose herewith the deed for your signature." That means you should expect to find the deed (a type of formal legal document) in the same envelope.
Nobody ever uses "herewith" in normal conversation, and I'm not sure you would even find it in rather old textbooks, as I think the meaning is always: "accompanying this", rather than what you can or should do with something.
I use it in everyday speech, but I'm weird. And I'm a lawyer. It's just so handy (also whereby, therefor, herein, whereto). And familiarity with those words appears to give me a bit of a leg up on Dutch.
But yes, they are a bit old-fashioned and, these days, formal-sounding. I blame William the Conqueror.
Well, loosely, it's "with", but that doesn't mean it can be used interchangeably with "met". It can be part of a separable verb, e.g. meezingen (to sing along): https://www.duolingo.com/comment/5585385.
Duolingo also has it in this example: https://www.duolingo.com/comment/9656524
"To take someone along" (i.e. on a trip). I'm not absolutely sure, in the latter example, whether it's a word in its own right, or it's actually another separable verb: meenemen.
Note that when it's used in the "along" sense, it's still always in the sense of: "with". You can't use it to say: "along the corridor".
"With this", "with that", "take along (with)", "sing along (with)"...
If I ask you to translate sterren en dromen and you translate it as dreams and stars it is impossible to know if you translated sterren as dreams or if you just decided to change the word order yourself for whatever reason.
Unless it is a set phrase or unless the word order of a sentence does not allow for it stick to the same word order as the language you are translating from.