Scales are a huge topic that applies not only to guitar but to all music. Like most things in guitar, getting overwhelmed by the topic of scales is practically unavoidable and may actually be the essential first step to understanding them. Trust your own ability to learn and work patiently. The huge mountain of info on scales will start to make sense EVENTUALLY, you just have to give the key concepts time to sink in a bit. …You also have to get started right away and stick with it.
I have several books and pdfs filled with hundreds of examples of scales, but most of them do a very poor job of explaining what a scale is or why we need to learn them. It is really funny how the terms these books use to describe scales are so esoteric the only people who can understand their descriptions are people who already understand what is being described! I have read many books and I wish I could tell you one that would answer all your questions about scales, but I can’t.
But maybe I can outline the key things to always remember as you are researching scales: