One of the basic umlaut confusions that beginners of Swedish come across is this one:
Swedish: man (English: man) vs. män (English: men)
With the umlaut, the world becomes a plural. While this might be confusing to some, there is a correlation in English: Man, singular, vs men, plural. The pronounciations, also, are almost similar to Swedish. But that one threw me for a loop first time I saw it!