Actual grace is, in Catholic theology, a supernatural help of God -- Divine grace -- for salutary acts. It is contrasted with sanctifying grace, which is a state of being that can be permanent, in that it consists only in a passing influence of God on the soul.
For example: if a person has, by grace, developed the will to follow the teaching of Jesus, "turn the other cheek", then if in the moment of an assault they choose to turn the other cheek, they may hope for the grace to actually turn the other cheek. Hence the term, "actual" grace, because it is given for action, as opposed to altering a person's state (cp. Sanctifying Grace). However the distinction is not total since actual grace can lead to righteous action and good works. (Cp. justification by works.)
There is a biotheological analogy between spiritual growth and grace and plant growth and sunlight, in that sunlight provides the power to actually photosynthesize and grace provides the power to actually do good deeds.