what does irony mean? what where some of the adventures?

A simple definition would be the use of words to convey a meaning that is the opposite of its literal meaning: the irony of her reply, “How nice!” when I said I had to work all weekend.

Did you mean irony in his adventure? I think Huck learns that the best person he knows happens to be an escaped black slave. The irony is that Huck finds a kindred spirit not in any of the white characters he meets or even in his old pal Tom Sawyer. Instead he finds his best friend in Jim.