The Moon is associated with subconscious fears, darkness, secrets, mistakes and mood swings. The Sun card symbolizes clarity, children, success, vitality, but it also warns against excess, arrogance and burnouts. The combination of the Moon and Sun points to polarities or progressions, like the passage of time.
The elements of the cards are Water (Moon) and Fire (Sun) and are in contrast with each other. Both cards are extremely powerful and it's not easy to say which one wins, unless we examine the rest of the cards of the spread. However, since in this case the Sun comes after the Moon, the combination gravitates towards a rather positive interpretation.