How does luciferase help an animal communicate?

Luciferase is an enzyme that's part of the light-producing process in living organisms capable of bioluminescence.

Organisms that can bioluminesce include marine vertebrates and invertebrates, fungi, bacteria plus terrestrial arthropods such as fireflies. Light can be bacteriogenic (from symbiotic relationships) or autogenic from the organism itself.

Bioluminescence is a chemical reaction between a light-emitting molecule (luciferin) and an enzyme (luciferase). Luciferin and luciferase are generic names. Luciferase catalyses the oxidation of luciferin to produce light.

In bioluminescing, organisms signal others in their species, mimic other species or help camouflage themselves.

https://en.wikipedia.org/wiki/Bioluminescence