Can't be luggage?
I would ask the same about "baggage"!
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!
Yes, 'to' can often be used both for this and that.
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
Hm... okay, let's add it.
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.
Added "case", this should have been accepted. But "backpack" is "plecak".
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.