Why are we called a covenant people?
This is a great question. Thank you for coming to Gramps for answers. Typically, I would answer the question as I understand it using scripture or official talks from the Leaders of the Church.
In this case, I will provide you with some quotes and actually direct you to the Official page of the Church where you can read them more in-depth. There they more eloquently and quite simply explain this terminology within the gospel.
“One of the most important concepts of revealed religion is that of a sacred covenant,” he said. “A covenant … is a sacred promise with God. He fixes the terms. Each person may choose to accept those terms. If one accepts the terms of the covenant and obeys God’s law, he or she receives the blessings associated with the covenant.” (Elder Russell M. Nelson)
“Every member has made the covenant in the waters of baptism to be a witness for God. Every member has made a covenant to do works of kindness as the Savior would do. So any call to bear witness and to care for others is not a request for extra service; it is a blessing designed by a loving Heavenly Father and His Son Jesus Christ. They have provided such calls as well as other settings, sometimes without a formal call, all for the same purpose. Each is a chance to prove what blessings flow from being a covenant people, and each is an opportunity for which you agreed to be accountable.” (President Henry B. Eyring)
“Divine covenants make strong Christians. I urge each one to qualify for and receive all the priesthood ordinances you can and then faithfully keep the promises you have made by covenant. In times of distress, let your covenants be paramount and let your obedience be exact. Then you can ask in faith, nothing wavering, according to your need, and God will answer. He will sustain you as you work and watch. In His own time and way He will stretch forth His hand to you, saying, ‘Here am I,’” (Elder D. Todd Christofferson)
I hope you take the time to read over the explanation and pray to Heavenly Father to obtain your own understanding of she knowledge.