The people renew the covenants here with God, both the one given at Sinai and the one given in Moab. Every incident during the 40 years in the desert would see more added to the law, like when the golden calf was worshiped and the priesthood was removed from the first born of all the people and given to the Levites exclusively. So it was with worshiping of Baal at Peor while they were encamped at the plains of Moab, it brought more restrictions down upon them as a consequence for their actions. And now all these new laws must be ratified and accepted just like the original ones were at Sinai.
They are reminding once again that God is faithful, and that all his promises will be kept, either in the form of blessing or curses. It’s made abundantly clear to them that they have the free will, and the capacity of thought, to chose which direction they’ll go. He tells them that the options are life or death, blessings or curses, and exhorts them to chose life.
The disciples ask Jesus to teach them how to pray, like John the Baptist taught his followers. This doesn’t mean they didn’t know how to pray at all, it means they wanted to be taught how their teacher prayed so they could emulate him. Jesus here teaches them what we now call the Lord’s Prayer, or the Our Father, and it’s a bit shorter in Luke than it is in Matthew.
Even though it’s shorter, it retains its essential properties. It’s a prayer that recognizes the holiness of God, praying for the coming of his kingdom, and asking for our daily sustenance, both physical bread and the supernatural Bread of Life. See The Perfect Prayer
Another very important component of the Lord’s Prayer is the recognition of the duty to forgive, because we’ve been forgiven. Jesus tells us many times that an unforgiving person is an unforgiven person.
Jesus then instructs them to be persistent in prayer and ask for whatever we need. This part of the gospel has been twisted beyond recognition to make God into nothing more than a genie with unlimited wishes. That’s not what Jesus means here, he’s telling us that ask for whatever we need and to persevere in prayer but all answers to prayer are contingent on the will of God.