'Miss out' usually just means the same as 'leave out', as in 'People often miss out apostrophes', but it's also used more informally to say that someone has missed an opportunity. For example, 'Anyone who doesn't come to the party will miss out!' 'Miss out on' is used exclusively in this way, to say that someone has missed a particular thing or opportunity e.g. 'Students who don't attend our classes will miss out on a great learning experience'. So, as Marissa says, 'miss out on' is used to talk about something specific, but 'miss out' would be more natural when the speakers know what it is that is being missed. In the example of 'Anyone who doesn't come to the party will miss out', you could also say 'Anyone who doesn't come to the party will miss out on a great time' and it would mean the same thing but I would say that the first example is more natural because it is obvious what people will be missing. Likewise with the second example, you could say 'Students who don't attend our classes will miss out' but if someone wanted students to attend their classes they would probably want to tell them exactly what they were missing out on! Hope that helps!

Miss out on (something specific) or miss out (what you missed out on is already known to the listener). I'll miss out if I don't go! (for example) Or You'll miss out! ( Both people know what is being missed. I'm not sure I provided any help