Simplify the following text for a Grade 7 native English-speaking person.
Original: In Yucatan and other parts of rural Mexico , the league is still commonly used in the original sense of the distance that can be covered on foot in an hour , so that a league along a good road on level ground is a greater distance than a league on a difficult path over rough terrain .
Simplified: In the Mexican countryside the league is still commonly used in the original sense of the distance a person can walk in an hour . So a league along a good road on level ground is longer than a league on a difficult path over rough ground .