Hello!
In the sentence: If they have the time and energy, Dina and Maggie will prune and water the shrubs, water is best described as a compound predicate.
To understand why, we need to understand what a predicate is.
Predicate can best be understood as part of a sentence that talks about the subject, and contains a verb.
In this particular sentence, water is a verb because it is an action of watering.
