I wandered lonely as a Cloud That floats on high o'er vales and Hills,
The speaker describes how he walked around and felt as lonely as a cloud. He doesn’t say, "walked around," but uses the much more descriptive word "wandered."
"Wandered" means roaming around without a purpose, like when you explore something. So it’s not necessarily a bad thing. But in its metaphorical use, "wandered" can mean feeling purposeless and directionless in general. As in, you have questions like, "What’s the meaning of my life?"
The first concept that we want to take a look at is that the cloud is "lonely." Asking questions about what this means will help us get into the poem.
Are clouds lonely? Well, maybe the ones that float about valleys ("vales") and hills are lonely. It's more likely, the speaker is projecting his own loneliness on the clouds. But that still doesn’t explain the strange image, because clouds usually travel in groups. (Except in cartoons where you can have a single rain cloud following Wiley E. Coyote around just to ruin his day.)
Maybe a cloud is lonely because it is so far above the rest of the world. Its thoughts are just so "lofty," and maybe the speaker’s thoughts are, too.
Also, the cloud could be lonely because it floats over a natural landscape with no people in it. Maybe the speaker has thought of hills and valleys because he happens to be "wandering" through such a landscape.
These are some of the questions we’re hoping the poem will help us sort out after this mysterious beginning.
When all at once I saw a crowd, A host, of golden Daffodils;
Suddenly ("all at once"), the speaker sees a group of daffodil flowers. We tend to think of daffodils as "yellow," but he uses the more majestic-sounding "golden."
He calls them a "crowd," so they must be packed tightly together. Then he elaborates on "crowd" by adding the noun "host." A host is just a big group.
Yes, "host" and "crowd" mean pretty much the same thing. Ah, but that’s where the connotations come in, those vague associations that attach to certain words. A "crowd" is associated with groups of people, while "host" is associated with angels, because people often refer to a "host of angels." Coupled with the description of their angelic "golden" color, we seem to be dealing with some very special daffodils.
Beside the Lake, beneath the trees, Fluttering and dancing in the breeze.
He sees the daffodils beside a lake and underneath some trees. It’s a breezy day, and the flowers "flutter" and "dance" on their stems.
Maybe now is a good time to step outside the poem for just a second to note that Wordsworth lived in a part of England known as the Lake District, which is filled with lots of hills, valleys and, of course, lakes. We can assume he’s walking in a fairly remote and wild part of the countryside.
Now, back to the poem. "Fluttering" suggests flight, which could bring us back to the angels or even birds or butterflies. "Dancing" is something that usually only humans do. The daffodils are given the qualities of humans and also of some kind of otherworldly creatures, perhaps.