The itinerary lasts 1day 3hrs 00min, and has 2 steps, and it will cost 48 euros minimum.

Brussels - Berlin
The step from Brussels to Berlin lasts 11hrs 30min. You'll travel in a night train.

Berlin - Stockholm
Take the train to Berlin at 6:34 p.m. to arrive in the Swedish capital at 9:55 a.m. the next morning!
The step from Berlin to Stockholm lasts 15hrs 30min. You'll travel in a EuroNight operated by SJ.
You can find tickets from 48 euros.