Peers are a couple of people who are at the same level in any educational area, such as students in a classroom. As Chris Drew said: " Peers can learn with each other, learn from each other, and one learns from the other." "Peers should both be students, each gets something educationally beneficial out of the collaboration and be equals either in terms of ability level or status as ‘students’. "
There are many different ways in which peer-to-peer learning can take place, Here are some examples. The senior students can act as a helper to the teacher and teach the materials that they've already passed in previous semesters and guide other peers on how to perform the best in that course, or the smarter student helps the student with an average level of skill in a class. It has been said that when we put a smart student next to a kind of not-so-clever student, the smart one will influence the other one and the progress of the not-so-intelligent one is highly probable. Peer-to-peer learning can be in the format of an assessment in which each peer checks the other's work and gives useful feedback which can be beneficial in the way that they can get familiar with different perspectives and strategies for doing the due assignments. Another example can be the projects that the teachers asked the students to do as a group. In this way, students are going to observe each other's perspectives and also discuss the skills that they bring to the project.
Besides positive perspectives that this method would have, there are some challenges that it may face, such as distractions that working in a group may have for some students or it might happen that the students do not show a respectful reaction to the feedback that their peers give to them about their work. However, the advantages of this method may be more than its disadvantages, not to mention that social learning and sharing of knowledge are just the first benefits that come to mind.
Peer-to-peer learning can be practical in workplaces too. It happened to me that every time that we do some projects in our office alongside my colleagues, more progress was generated than when done individually. I really get the benefit of my co-worker who is more experienced than me and his feedback helped me to find and correct my mistakes creating a better outcome.

https://helpfulprofessor.com/peer-learning/
https://www.togetherplatform.com/blog/a-guide-to-peer-to-peer-learning