This is the third and last volume in the omnibus edition of the Navarre Bible New Testament (the others being The Gospels and Acts and The Letters of Saint Paul).  It contains two quite disparate books of the Bible:

The Revelation to John (Apocalypse), the last book of Holy Scripture, which focuses largely on the second coming of Christ and the End times.

The Letter to the Hebrews. One of the most imposing and important books in the New Testament, its teaching hinges on Christ, God and man and high priest of the New Law. The Church makes much use of this book in her liturgy.

and

The Catholic Letters: this is the description often given to seven New Testament books not attributed to St Paul and (mostly) addressed to the whole Church rather than specific churches or individuals.  These books are: James, 1&2 Peter, 1-3 John, and Jude.