Hazel McKay's "Eagle" is a short, quiet poem about imagining life from a higher place. The speaker watches, or pictures, an eagle soaring above the hills and thinks about the view it must have. Nothing dramatic happens. The poem is really a moment of daydreaming.
The speaker feels curious and a little wistful. The line "How wonderfully small the world must feel" suggests that being so high up might make everyday worries shrink, and that idea seems to appeal to them. Notice that the poem is full of "must": the speaker can only guess, because they are stuck on the ground and cannot know.
The mood is calm, gentle and dreamy. The ending adds to this. The word "Eagle" sits alone on the last line, as if the thought drifts off and the bird itself floats away on the page. The poem closes on a wish rather than an answer.