A Shore Excursion Guide provides the on-land experience for cruise guests. Once the travelers have left the ship and are on the ground, the Shore Excursion Guide gathers them together, explains the nuts and bolts of this particular shore excursion, and proceeds to organize the tour. Some mode of transportation likely is in order, perhaps a van, perhaps a bus with a sound system.
Whatever it is, the Shore Excursion Guide moves the group aboard, explains safety issues, talks about what they will see and do, and moves the group out to the activity. The Cruise Host, who travels on the ship with the guests, may or may not come on the tour, if there are multiple tours occurring simultaneously.
After saying good-bye to one group, the Guide will work with another, from this cruise ship or the next, and will repeat these assignments throughout the season. It is likely that the Guide is a local. The job is likely to pay an hourly wage plus tips.