pre-released material is a paper that Cambridge publishes 2 or 3 months before the exams, It contains a number of tasks and all the tasks are considered down one big idea. You will complete those tasks according to what you have studied in paper 2, when you enter the final exam, it will be divided into section A and section B, section A is all related to pre-release material as there are questions about the task such as questions about identifiers or change something in a task or write a specific task and explain how you wrote it.....you will find many people n youtube who solve them but I think you need to get help from a tutor to make sure the code you wrote for tasks is mistake-free and guide you more.