This is just my interpretation, but it seems to me that the first stanza is saying that life is not our most natural state of being -it is awkward and uncomfortable, and we sort of stumble through it by necessity, much as a swan on land. However, when we die (the remainder of the poem) we are in our element, as when the swan hits the water. Then we are free and fluid, released from the necessary burdens of life. I think this poet must have strong religious beliefs. At least, that's what I gather from it.
This poem was about how when a swan gets out the water it has a hard time walking on land. But when the swan gets in the water it is easier for them to walk and swim freely. It basically describes how a swan experiences on land and in its natural home, in the water. In my own thinking I believe that this poem refers to the human life. It tells a story how our life compares to a swan. Such as when a swan is on land it has trouble walking and in life we stumble at times but we get back up on our feet and continue to walk. When the swan goes into the water it's free like when we die we are free as well. We let go of the pain that we carry every minute of our lifes and we are just free and happy.