There is a whole series on modes in the PMT course (video text the lot), which as Keith says is a pay for course. From experiences. limited, you need a fairly extensive knowledge and ability to apply the major scale(s) and understand the CAGED system, before getting into modes, so not surprising that this is not something Justin covers at a beginners level. In fact its kinda post Intermediate in terms of progression playing wise. So from my perspective once you get to that level, your interest in the theory side of thing gets far more inquisitive and that's when you start digging into this stuff. Again from my experience from completing the BC, IM, CAGED and Master The Major Scale I have achieved a rudimentary knowledge of Modes. For example I know that each Modes root is an interval from its major scale, the minor scale Aeolian starting from the 6th interval of the parent major. But to be honest that's after a good few years of development and as a beginner or even at the end of the BC, those concepts would have just blown my mind and I would have been incapable of applying the knowledge let alone retaining it.
For me that why Justin's structured approach to teaching is the key to success, as he will only introduce these kind of topic as and when folk are ready for them and not before.
As a beginner I would not worry about them for now. work through the BC, IM, MTMS, CAGED and along that route start the PMT course - yes you have to pay but its is value for money and just look at everything else that is provided gratis - you will the get to know modes when the time is right.
This is a slow long walk and not a race, take your time.
Cheers
Toby