Fig.: to move in a clumsy and awkward way, especially when dancing

I adore dancing, but I've got two left feet and I'm too embarrassed to accept invitations to dance

Io adoro ballare, ma ballo come un orso perciò non accetto mai inviti perché mi vergogno troppo

“This is the prom! Why aren't you dancing?” “Because when it comes to dancing I have two left feet”

“Siamo al ballo di fine anno! Perché non balli” “Perché in fatto di ballo sono una frana”

Having two left feet, which are not symmetrical, would lead to lack of coordination, unbalance and stumbling when moving.
This expression originated in the early 1900s in the world of dance and referred to dancing only, but today it can be applied also to different situations, such as running, playing a sport, performing difficult physical jobs, and so on