Question

A man is passing through an unfamiliar place and the sign board is uprooted how did he find out where to go

Answer 1

The only way he would know where to go is if he asks the people around that place, if there are any, for directions. He then can be directed by a good Samaritan on the right route to take. The only other option would be to guess the route to take, this however would not be the most appropriate decision to make. 

Answer 2

On the sign board , it is shown that you are coming from this route, you are standing here.  The person is coming from city D to the junction.
 
   Then it is shown that to the right side, there is city A, to the left side city B, and straight ahead  the city C.

Since the person knows the route he/she came from, if she/he erects the sign board, he knows which direction to go to.

He/she need not ask any person.