The Fifth House is the house of creativity, pleasure, and self-expression. It is the house of children (both literal children and the creative works that are one's "children"), of play, of romance, and of the pure joy of being alive. It is the house where the self is displayed, not for status but for the sheer pleasure of expression.
In traditional astrology, the Fifth House is called the House of Children (or Good Fortune). It describes your relationship with children, your experience of romance and courtship, and your capacity for joy.
A planet in the Fifth House describes how you express yourself creatively. The Sun in the Fifth House is at home, giving a natural warmth, confidence, and creative flair. Venus in the Fifth House gives an appreciation for beauty and pleasure, and often artistic talent. Saturn in the Fifth House may indicate difficulty with creativity or pleasure, a tendency to take play too seriously, or delays in having children.
The Fifth House is naturally associated with Leo and the Sun: the sign of creative expression and the luminary of vitality. When planets are placed in the Fifth House, they take on something of this Leonine quality, becoming more expressive, more playful, more focused on the self.