Prudence is the ability to use reason and good judgement to manage oneself. The opposite of prudence is rashness or, more generally, foolishness. An example of prudence would be saving money or other goods during profitable times in order to have something to fall back on in more trying circumstances (Joseph set a good precedent for this as viceroy of Egypt).
In Christian tradition, prudence (or wisdom) is one of the four cardinal virtues. Solomon is the foremost example of this virtue, before his wives turned away his heart imprudently toward other gods (1 Kings 11:1-11).