"Swedish" is an adjective, "Swede" is a noun specifically for people from Sweden.
eg. "He is a Swedish person" or just "He is a Swede". You could also say "He is Swedish", but here you are technically just describing the type of person he is. Very subtle difference. The same is for Dane vs. Danish.
For some reason, calling someone "a Swede" makes me cringe a bit and I doubt I'd use that expression. I submitted "Swedish person" and it was marked wrong. This is a year after your comment, too. I've reported "Swedish person" as potentially correct, since it could be either a man or a woman here.
'mlt' is 'with' in english not ',to'. Is the purpose to translate the sentence as it is written or not ?
According to this
a male or unspecified gender Swede would be Schwede and a female Swede would be Schwedin. Google Translate seems to concur, though depending on the phrase it also uses Schweden, but particularly when the gender is not clear.
Can someone clarify when to use each of these three nouns?
New edit: ok, so I found out that den/dem/des Schweden can also be used for the masculine of all cases other than nominative, because Schwede is a weak noun. I had not opened the declension box in the wiktionary reference, and I'm still getting up to speed on the complications of weak nouns...
Possible context for 'Are you talking to the Swede?': They have a bunch of Swedish people (only swedes, nothing but swedes) locked up in a very, very dark place and one day one captor finds out, much to his surprise, that one of his fellow kidnappers is actually having a chat with them. They're talking about politics and contemporary art in a very relaxed tone and captor #1 suddenly flies into a fit of rage before this outrage, thus articulating this very sentence.