Sheep are animals that use the hopping-around-Walkstyle. They are herbivores and are the first animal you unlock when playing the game, from the task My First Tree. They are often hunted by predators like the wolf.
Sheep are the first animal, and therefore also the first source of DP income. The easiest way to make stable DP from sheep is to have a grassland patch filled with grass tufts and trees, and have it inhabit as many sheep as the resources can support. Although the DP output of a sheep is relatively low, having enough of them can provide you with a basic source of DP and slightly higher amounts of the currency can be saved up.
After progressing and acquiring the wolf species, you can boost the DP from the area even further by adding some wolves to the grassland, or somewhere near, as long as the location where you place their home is above 35 meters in altitude. They will then start hunting the sheep for food and producing much more DP than the sheep alone.