Misplaced modifiers don't describe or explain the words the writer intended them to—instead, they accidentally describe or explain something else.
A misplaced modifier often appears to modify the wrong word or can leave the reader totally confused as to which word it actually modifies. Fortunately, most issues with misplaced modifiers can be fixed in a snap simply by moving the word being modified closer to the modifier.
Example
Pam adopted a puppy from an animal shelter named Morpheus.
The misplaced modifier in this sentence seems to suggest that the animal shelter was named Morpheus...which is obviously not what was meant by this sentence. (And we would know; we wrote it.) The modifier named Morpheus should be placed next to what it modifies: a puppy.
This sentence should be something like:
Pam adopted a puppy named Morpheus from an animal shelter.
There we go.