One of the most remarkable linguistic similarities between English and Portuguese is the way one can react to comments and statements by speaking "uh", uh-uhum", "mmm...", to mean "I'm listening", "I agree"or"that's right", or to show surprise, anger or happiness when saying "wow" or "oh". Though these "words" differ their spelling they pretty much sound the same in the Portuguese language and have very close if not equal meanings. "Ãh", "Ãham", "mmm..." are our equivalent to the first group and "Uau" and "Oh" match the second one.
We also imply basically the same things when using these expressions.
So, here's what even very elementary English students would call an easy lesson.