The poet here in a very minute way discusses the incidents and actions happened in spring time. The poet says that he can feel the gentle calm air of the spring time. The birds are singing and chirping because they can fly now in the 'unclouded' sky. This term 'unclouded' is suggesting that before the coming of the spring, it was raining for sometime. However, now the birds are happy to see the unclouded bright sun. 

In the 2nd paragraph, the poet more clearly expresses how happy everybody was with the coming spring. The children are playing and dancing in the meadows, they are collecting different kinds of flowers which are available during this time like primroses, bluebells, oxlips etc.

The last paragraph is all about the innocent mischief doing  by the children. The woodman is cutting woods beside his "Willow hut" and the children are planning to make him terrified by hiding behind his hut. Not only that, they also want to sing Happy song after doing this naughtiness. Here it is clearly shown how innocent and pure they are. 

The whole poem is written in a light-hearted manner. Nothing is serious. But the poem is completely rhythmic in its own way. The poet uses many alliteration here to give the poem a beautiful structure. He usese the phrase like "blades of bluebells" and "boughs to burst" etc. The language of the poem is quite simple and straight forward.