One feature of a flower that tries to attract the Hummingbird moth is a strong, sweet odor, which helps signal to the moth that there is nectar available. Flowers that adapt to the needs of more than one pollinator can be more reproductively successful because they increase their chances of being visited by different animals. For instance, if a flower also attracts bees or butterflies, it won't rely solely on the Hummingbird moth for pollination. This means the flower can produce more seeds and grow more plants, increasing its chances of survival.
To explain it to a 7th grader: Imagine a flower is like a restaurant. If it only makes food that tastes good to one specific customer, like the Hummingbird moth, it might not get many visitors. But if it makes food that tastes good to lots of different customers, like bees or butterflies too, more animals will come and help the flower make seeds. This can help the flower grow and spread more!