Leo as a moon or rising sign
Sun signs are just one facet of your personality, your general temperament. The rest of your chart also plays a role. If Leo is your Moon sign, it affects your inner or emotional self ... maybe it means that your quiet exterior is masking a fountain of creative and imaginative energy. If Leo is your Rising sign, it might mean that you present a very vibrant and fiery exterior in public, even if you are more reserved in private.
If you have questions on what it means to have Leo in your chart, this is the place to ask them!