A Roman Catholic devotion is a gift (total or partial) of oneself, or one's activities to God. It is a willingness and desire to dedicate oneself to serve God; either in terms of prayers or in terms of a set of pious acts such as the adoration of God or the veneration

Veneration

Veneration , or veneration of saints, is a special act of honoring a saint: an angel, or a dead person who has been identified by a church committee as singular in the traditions of the religion. It is practiced by the Eastern Orthodox Church, the Roman Catholic, and Eastern Catholic Churches...

 of the saints or the Virgin Mary.

Roman Catholic devotions are "external practices of piety" which are not part of the official liturgy

Liturgy

Liturgy is either the customary public worship done by a specific religious group, according to its particular traditions or a more precise term that distinguishes between those religious groups who believe their ritual requires the "people" to do the "work" of responding to the priest, and those...

 of the Catholic Church but are part of the popular spiritual practices of Catholics.