Answer:
Juxtaposition basically means comparison/contrast (n.).
Juxtaposition is a noun, so naturally it can follow an article (a, an, the) and/or an adjective (as well as genitive nouns), and it can be placed before a relative clause or in another noun phrase in the sentence.
For instance:
The juxtaposition between frogs and toads is negligible.
The student argued against the teacher's blatant juxtaposition of the subject material.
In verb form:
I juxtaposed the music from the 60s to the music of the 70s.