Literal meaning, rarely used outside the idiom 二の足を踏む. In modern Japanese, this sense is mostly encountered in explanations of the idiom.
In the idiom 二の足を踏む, 二の足 literally means the second step.
Used almost exclusively in the set phrase 二の足を踏む, meaning to hesitate or be unable to make a decision. The phrase evokes the image of taking one step forward and then pausing before the second step.
See also: 二の足を踏む
I'm hesitating about whether to apply for the new job.
He always hesitates when making an expensive purchase.