Vatican website translation:

51. The treasures of the bible are to be opened up more lavishly, so that richer fare may be provided for the faithful at the table of God’s word. In this way a more representative portion of the holy scriptures will be read to the people in the course of a prescribed number of years.

Latin text:

51. Quo ditior mensa verbi Dei paretur fidelibus, thesauri biblici largius aperiantur, ita ut, intra praestitutum annorum spatium, praestantior pars Scripturarum Sanctarum populo legatur.

Slavishly literal translation [thanks to Jonathan Day]:

51. In order that richer fare may be provided to the faithful at the table of the word of God, the biblical treasures are to opened up more lavishly, in such a way that in the course of a prescribed number of years, a more surpassing part of the holy scriptures may be read to the people.

Article 51 decrees that the [Roman Rite] liturgy is to be reviewed and reformed in such a way that more biblical material is made available to worshipers. Respecting Jared Ostermann’s remarks on my re-reading of article 50, I will attempt to be both careful and irenic in my presentation of this decree. In the light of the biblical renewal experienced in Roman Catholicism especially in the years after Pius XII’s Divino Afflante Spiritu, the Council Fathers judged that the amount and variety of scripture available to [Roman Rite] worshipers, while able to sustain piety, could have even more powerful effects were it to be increased and deepened. While the shift from a single-year lectionary system with Epistle and Gospel readings to a three-year Sunday and solemnity system with Old Testament, New Testament non-Gospel, and Gospel readings conjoined to a two-year weekday lectionary system with Epistle and Gospel readings for Mass may be the most obvious result of article 51, the lectionary offerings for all sacramental celebrations and for the Liturgy of the Hours have in fact been “lavishly” increased. Pray Tell readers may wish to discuss how effectively these reforms have borne fruit in the last fifty years and what might make them more effective. Conversely they may wish to discuss the advantages hidden to the Council Fathers of retaining less lavish scriptural fare in [Roman Rite] worship.