Is a colon used to separate syllables at the end of a line? Is a hyphen only used to join compound words?
No, and no.
Colons are used to introduce a list ("There are three choices: red, blue, or green.") and are used to separate independent clauses when the second illustrates or explains the first. ("I don't have time to learn French: my life is too busy.")
The colon is never used to separate syllables of a word between lines; that job is always reserved for the hyphen, which is one of its many jobs in addition to joining compound words.