The Haftarah of VaYikra, like many other Haftarot, are taken from the Chapters of Comfort in Yeshayahu .
Linear annotated translation of the Haftarah of VaYikra
While it mentions sacrifices, which is the topic of the Parsha, what it is really about is the relationship between G-d and the Jewish People.
In particular, it shows us what the relationship is not.