Presbyterorum ordinis is a big important word that means getting special training to become a Catholic priest. Just like how doctors have to go to school to learn all about taking care of people's health, priests also have to go to school to learn how to help people with their spiritual health.
When someone wants to become a priest, they have to go through some special steps. First, they have to go to school to learn about God and the church. Then, they have to go to another special school where they learn how to be a priest, like how to give Mass, how to listen to people's problems, and how to help people understand the Catholic faith better.
After they finish all this training, they become "ordained" which means they are officially a priest for the Catholic church. Once they are ordained, they can do special things like baptize babies, give communion, and help people with their sins.
Presbyterorum ordinis is a big deal because it helps make sure that Catholic priests are really good at what they do and can serve people in the best way possible. It's like making sure that doctors are really good at their jobs before they start taking care of patients.