Well, a suitcase doesn't have to be baggage. It is baggage only during a journey. You wouldn't use the word "baggage" about a suitcase that is in your house, or in the shop.
I know that "to" means "this," but in this case, is
That's my suitcase!
I've never said 'suitcase' in my life. When I travel I take a 'case' or a 'backpack' and I've been speaking English for 70 years. I wish duolingo would stop correcting my English!
We must be from different regions, because I am the exact opposite of you. I've always called it a "suitcase," never used the word "case." A backpack is an entirely different thing. Calling luggage "bags" is very common here too.
Sorry I didn't explain myself very well, I didn't mean to imply that 'walizka' should also cover backpacks. I was only referring to the word 'suitcase'. Thanks for adding case.
Hey...I wonder if you could translate this to It's my bag? yes pretty informal I guess but this is how I would say it in English
Bag can be used for luggage or suitcases of many sizes but say in the context of pointing at a piece of luggage I would say 'it's my bag!' say if someone was attempting to steal it