In the fourth petition, by saying "give us," we express in communion with our brethren our filial trust in our heavenly Father. "Our daily bread" refers to the earthly nourishment necessary to everyone for subsistence, and also to the Bread of Life: the Word of God and the Body of Christ. It is received in God's "today," as the indispensable, (super - ) essential nourishment of the feast of the coming Kingdom anticipated in the Eucharist.
Source: Catechism of the Catholic Church (Vatican.va)