Signposts are signs by the road that show you where to go.
Signposts are helpful because they tell you which way to go.
Examples:
The signposts tell us how to get to the park.
We need to follow the signposts to find the museum.
The signposts are very clear and easy to understand.
The signposts are like a treasure map for the road.
The signposts are like friendly helpers showing us the way.
The signposts are like magic arrows pointing the way.