Revelation is one of the hardest books to understand in the Bible—in fact a lot of believers skip it even though it tells us those who read it are blessed. One of the reasons it is hard to understand is because it is prophetic in nature, requiring us to determine what parts are symbolic versus literal. Another reason it is difficult is the fact that we don’t agree on what has and hasn’t taken place yet, making it difficult to align times and events. There are four differing schools of thought or frameworks that are used to interpret Revelation: Preterism (the belief that everything happened in the past), Futurism (the belief that everything will happen in the future), Historicism (the belief that most things have already happened, some things are happening, and others will happen in the future), and Idealism (the blief that none of this is about a specific event, but rather a symbolic concept). You can read more about these frameworks in Major Schools of Thought on Interpreting Prophecy.
