Basically, "kein/e/n" negates a noun, e.g.: Ich habe kein Geld (I don't have any money/I have no money) Er trägt keine Jacke (he isn't wearing a jacket/He is wearing no jacket) Ich möchte keinen Tee (trinken) (I don't want (to drink) any tea) while "nicht" negates the verb (or the whole sentence), e.g.: Er kann nicht schwimmen (he can't swim) Er schläft nicht (he's not asleep) There is no way to replace "nicht" with "kein" in the sentence "Ich komme nicht aus Deutschland", because "kein Deutschland" would mean that there is no Germany, that Germany does not exist.