This idiom says that it is not possible for one person to achieve something. There is a need for minimum two persons to come together and achieve. Example - (a) How do you expect him to complete the work alone, it takes two to tango. (b) Do you mean she has done it by her self, I am not sure. It generally takes two to tango.

I have also observed that idioms has potential to understand many personality related aspects, if we explore its meaning and try to go deep inside it. It definitely reveals some thing unexpected.

This idiom also emphasizes dependency of each one of us on some one else. It can be a human, animal, or any other element that exists in the universe. No one should develop a feeling that he or she alone is great and can create or complete some task all by himself or herself. Even if we want to life some thing it takes two (fingers) to tango !

Enjoy !

sunil