I have been using Rosetta Stone for a while now and understand what is going on... but one thing confuses me... why is 「なん」 used at the end of a sentence?
For example, a sentence I encountered has:
茶色のTシャツの方が好きなんです。
I do not understand why 「なん」 is used when it usually means a questionable "what?/Why?/How?" and so on.
May someone please educate me on its usage please?
Thank you :3