The phrase "to live off" means to rely on something or someone for support, sustenance, or maintenance. It can refer to a person who depends on an income, such as from employment or investments, in order to meet their basic needs and expenses. In this context, the term implies that the individual is able to sustain themselves financially through their earnings alone. The phrase can also be used metaphorically to describe someone who relies heavily on a particular activity, habit, or relationship for emotional fulfillment or satisfaction in life.