Final answer:
The sign indicates a 'litter disposal area' is one mile ahead, used for legally disposing litter on highways.
Step-by-step explanation:
The question you've asked pertains to traffic signage and law regarding litter disposal on the highway. The sign you are referring to indicates that there is a designated litter disposal area ahead where motorists are legally permitted to dispose of their litter. Such barrels are commonly found not just in isolation but also at rest areas, which often include picnic spots and other facilities for travelers. It is important to make use of these facilities to keep the highways clean and prevent hazards that can be caused by litter, such as those mentioned in the reference with cardboard pieces and the odor of urine in sheltered locations post-rain.