Not sure if this is a joke or a mistake since the English "glass" is "glas" in Swedish, but the Swedish "glass" is "ice cream" in English. The correct translation in Swedish would be "Jag kan äta glas, det skadar inte mig".
This is one of many silly sentences I heard while growing up, mainly from other Swedish kids who were learning English and finding silly similarities in words. So it's definitely deliberate.
Glas (glass) and glass (ice cream) have very different pronounciations that you don't really mix up. Glas has an extended a, glass sounds just about the same as in english.
To an Aussie bogan like me I'd pronounce the two the same usually, I have to think of the difference as how an American says glass vs how an Englishman/Aussie might say glass
I haven't had the balls to try speaking Swedish yet so haven't asked to eat some glass yet
I feel the urge to speculate that Swedish "glas" comes down from proto-Germanic, while "glass" is a loan from French "glace".