Which figure of speech is" The woods are lovel, dark and deep"?

'Dark and deep'. This phrase is an example of alliteration in the poem.

Alliteration is a term that describes a literary stylistic device. It occurs when a series of words in a row (or close to a row) have the same first consonant sound. For example, “Peter Piper Picked a Peck of Pickled Peppers” or “She sells sea-shells down by the sea-short” are both alliterative phrases. In the former, all the words start with the “p” sound, while in the later, the “s’s” take precedence. Aside from tongue twisters, alliteration is also used in poems, song lyrics, and even store or brand names.