Praesta, quaesumus, Domine,
ut, per quadragesimalem observantiam eruditi
et tuo verbo nutriti,
sancta continentia tibi simus toto corde devoti,
et in oratione tua semper efficiamur concordes.
A bit strange in its style, no? Well, this is of new composition for the Novus Ordo. It takes some inspiration from Sermon 40, 4 of St. Pope Leo I "the Great" (+461).
Erudio is "to polish, educate, instruct, teach". Rudis is an adjective for "unwrought, untilled, unformed, unused, rough, raw, wild". Someone who is rudis is "rude, unpolished, uncultivated, unskilled, awkward, clumsy, ignorant; hence (like ignarus)". People must be brought out of this state by being polished. St. Augustine (+430) wrote a work called De catechizandis rudibus. Eruditio refers to the whole culture and formation of a Catholic.
Observantia is certainly an "observance", but also "an observance of religious duties, divine worship, religion". For example, the Theodosian Code speaks of "fides Catholicae observantiae" (16, 5, 12, § 54).
Grant, we beg You, O Lord,
that we, having been polished by means of the Lenten observance
and nourished by Your word,
may by holy continence be consecrated with our whole heart,
and we may be made always harmonious in Your prayer.
Day by day our Lenten observance ought to be a polishing not a torture. Sometimes people make the mistake in the spiritual life of putting themselves on the rack. The rock tumbler is a better model than the rack.