1
general::
Be clumsy, as in I'll never get the hang of this dance; I've got two left feet. This expression conjures up an image of feet that are not symmetrical, as left and right are, therefore causing imbalance or stumbling. It was first recorded in 1915., see TWO LEFT FEET.
American Heritage Idioms
2
general::
Phrase(s): have two left feet
Fig. to be very awkward with one’s feet. (Often refers to awkwardness at dancing.) • I’m sorry, I can’t dance better. I have two left feet.
McGrawhill's American Idioms And Phrasal Verbs