How to properly describe experience in exchange program in Statement of Purpose in Master Application?
Actually, the SoP my be the wrong place for this information. The Statement of Purpose should be looking forward to your academic and career plans, not the past. The CV and other introductory material form a retrospective on your past.
Don't waste word in the Sop on things that aren't about future plans. The exchange program would only be appropriate there if it causes some change in your plans looking forward.
But a line or two in the CV would be a better place to mention it, with some simple phrasing (or not).
If you wind up in an interview, you can bring it up then. But give the SoP the impact it requires.