Pope Francis established this observance as a fruit of the Extraordinary Jubilee Year of Mercy (2015).  The purpose of the 24 Hours For The Lord is to emphasize that the Sacrament of Penance and Reconciliation is at the center of the pastoral life of the Church, and therefore of our communities, our parishes, and all ecclesial realities. This is the core of the Gospel message: the Mercy of God, which gives us the certainty that before the Lord no one will find only a judge, but rather will find a father who welcomes him, consoles him and shows him the way to renewal. Therefore, as the late Pope Francis stated, “Mercy give rise to joy, because our hearts are opened to the hope of a new life” (Misericordia et misera, No. 3). 24 Hours For The Lord is scheduled during Lent intentionally because of Lent’s focus on repentance and conversion from sin to the new life of grace in Christ.
More information can be found https://cathedralphila.org/24-hours-for-the-lord/