Describe an action as prudent if it is the wise thing to do under the existing circumstances. If you're getting in trouble, it is probably prudent to keep your mouth closed and just listen.
If you show good and careful judgment when handling practical matters, you can be described as prudent. Similarly, a wise and well-thought-through decision or action can be called prudent. The word comes from a contracted form of the Latin prōvidēns from the verb "to foresee." The English word provident "wise in planning for the future" is the non-contracted descendent of the same Latin root.