Only six words long, this poem asks you to slow down and fill in the rest yourself. It names one thing, a swing, and says it holds "all the beauties." That word is plural, and "all" makes the claim large. A simple playground object becomes a whole collection of small delights: the rise and fall, the moment of hanging at the top, the breeze, the rhythm of going back and forth.
The speaker doesn't describe any of this, so what they feel has to be read from the tone. It sounds fond and a little wistful, as if they are remembering or simply admiring. The line breaks, with their gaps of white space, mimic the pauses of a swing at the height of its arc, before it drops back. The mood is quiet, gentle and open-ended. Because the poem gives so little, your own memory of swinging does much of the work, and that may be the point.