The deploy goal of the Deploy plugin is usually
bound to the deploy lifecycle phase. This phase is
used to deploy an artifact to a remote Maven repository, this is usually
required to update a remote repository when you are performing a
release. The deployment procedure can be as simple as copying a file to
another directory or as complex as transferring a file over
SCP using a public key. Deployment settings usually
involve credentials to a remote repository, and, as such, deployment
settings are usually not stored in a pom.xml.
Instead, deployment settings are more frequently found in an individual
user's ~/.m2/settings.xml. For now, all you need to
know is that the deploy:deploy goal is bound to the
deploy phase and it takes care of transporting an
artifact to a published repository and updating any repository
information which might be affected by such a deployment.

