General Meaning: A comparison between the poet alone and a crowd of flowers.
Detailed meaning: The poet describes himself as a lonely cloud viewing the earth below,when suddenly he sees a host of Daffodils. He compares them in number as the stars, and outshining the flashes of sunlight on the waves. The sight filled the poet with joy. He also has the memory of the beautiful daffodils, to cheer him whenever he needs it.
Intention: To alert the reader to pay attention to the beauty of nature. This is because the viewer of nature retains the memory of the sight, to cheer him when needed.