beginner needs help with a strange marking

[haleyfranc]

I am a poor beginner who hasn't taken piano lessons since I was eleven, over twenty years ago. I got a piano this summer for my son, but as he is only two, I think I really got it for myself! Anyway, here I am plugging away at my Bach Minuet and I come across this symbol I don't know: it looks like a little squiggle above the note. It occurs about five times in this piece. What does that mean? Thanks!

[qoppa]

That squiggle is called a mordent.  It means that you quickly alternate between playing the written note and the note above.  They're similar to a trill, except you only play the alteration once.

[alwaystheangel]

this might help: https://en.wikipedia.org/wiki/Mordent

[desordre]

 Dear Haley:
 I have to add something to the above: in the Baroque Era the practice was to start (almost) any ornament with the upper note. So, if you have the mordent on a C (for example), actually what you have to play is DCDC, with a subtle stress (both agogic and dynamic) in the first D.
 Oh, by the way, enjoy your piano playing! 
 Best wishes!

[haleyfranc]

Thank you so much! I get it.