The text describes a symbiotic relationship, which is the relationship between two species were at least one of them benefitst.
There are three types of symbiotic relationships:
1) Mutualism: Both species benefit from the relationship.
2) Comensalism: One of the species benefits from the relationship while the other one is unaffected.
3) Parasitism: One of the species benefits (the parasite) while the other one is harmed (host).
In this case, the nummingbird benefits because it gets food from the flowers, and the flowers benefit because the hummingbird distributes the pollen facilitating the flowers reproduction.
Both species benefit for their relationship so it is "mutualism"