As the poem opens, the speaker describes the scene around the tower of Shalott. We realize this is an isolated setting outside of Camelot, surrounded by barley fields. Tennyson calls the barley "bearded" because ripening barley grows long, grassy bristles that surround and protect the barley grain, just as the bristles of a beard cover a face.
Tennyson also says the barley has grown over the head of the reaper. That it is tall, bearded, and being reaped or harvested means it is fully ripe and that the season is probably late summer. But Tennyson is really trying in these early stanzas to emphasize how isolated the area is. Not only is Shalott surrounded by acres of barley and rye, as both grains grow in England, it is surrounded by a moat as well.
Although the movie camera had not been invented yet, Tennyson is, in effect, "flying" in on the tower from overhead, giving us a wide shot of the entire scene in which the tower is set. At this early point in the poem, there is some suspense: Why is the "camera" from afar zoning in on this tower of Shalott?
Our first experience of the mysterious resident of the tower is not a visual of her but the sound of her singing, heard by the reaper amid the "bearded barely." He hears her "chanting cheery" (singing) as he works and identifies her as the Lady of Shalott.