This prayer asks for the grace to prepare well for death, passing from this world in peace.
Whether we like it or not, we will all die. It is the fate of all humanity, though we do not know the day or hour when this will occur.
This is why we should do all we can to prepare for the day, asking God for all the necessary graces to die in peace, instead of in desperation.
Here is a short prayer from the 19th-century prayer book The Raccolta, that asks God for help to live this life well, ready to depart it when our journey on earth has ended.
O God, who has concealed from all the hour of their death, grant that I may pass my days in the practice of holiness and justice, and that I may be made worthy to leave this world in the peace of a good conscience, and in the embrace of your love, through Jesus Christ our Lord. Amen.