A two-way street is a street that allows vehicles to travel in both directions. On most two-way streets, especially main streets, a line is painted down the middle of the road to remind drivers to stay on their side of the road. Sometimes one portion of a street is two-way, the other portion one-way. If there is no line, a car must stay on the appropriate side and watch for cars coming in the opposite direction and prepare to pull over to let them pass.

A two-way street can also be used as an idiom

Idiom

Idiom is an expression, word, or phrase that has a figurative meaning that is comprehended in regard to a common use of that expression that is separate from the literal meaning or definition of the words of which it is made...

atic metaphor to indicate that something goes both ways. For example, in this sentence: "Communication within the supervisor-employee relationship must be a two-way street that is heavily traveled in both directions."