This picture represents farming land that is rejuvenating.
The Mayans figured out that letting soil rest after being used to grow crops will help it stay healthy, regain nutrients, and maintain soil structure. This means that their crops will have more nutrients and they will be able to use the soil while it is healthy and nutrient-filled for longer.
They also grew corn.
This represents the same land being used to grow crops.
This picture represents Summer, one of the four seasons.
The Mayans made an accurate calendar based on the movement of the Sun and stars (really the earth moving). Their calendar had the same amount of days as modern day calendars do. Their calendar was correct up until 2012, when the calendar ended.
This picture represents winter. The two pictures represent the change of seasons, and the Mayans calendar.