Pratt's poem plays with small, ordinary words and treats them like places you can travel between. "But" is a hinge word, the one we use to swerve from one thought to another, and "blue" is a feeling or a faraway color. The poem asks what it takes to get from one to the other, and its answer is "your big jump."
The speaker sounds a little dizzy, "a little high on nothing," as if language itself has gone slightly loose. Nothing is quite spelled out, so the poem feels more like a mood than a story. There's a hint of comfort in "snuggle up," but it's set against "their nothing but," which suggests something dismissive or deflating. Moving on from blue is described as "a problem."
The ending loops back: you leave and return "by the next blue," making a circle. The effect is dreamy, a bit melancholy, and quietly repetitive, like a thought you keep circling without landing.