What does Psionic Mastery actually do?

This is part of the Psionic Mastery description from the Unearthed Arcana Mystic rules:

Beginning at 11th level, your mastery of psionic energy allows you to push your mind beyond its normal limits. As an action, you gain 9 special psi points that you can spend only on disciplines that require an action or a bonus action to use. You can use all 9 points on one discipline, or you can spread them across multiple disciplines. You can’t also spend your normal psi points on these disciplines; you can spend only the special points gained from this feature.

I think this explanation is lacking, and I didn’t find clarifications around.

When I use my action to activate this new type of psi points, do I also choose the disciplines I want, and they take effect altogether? Or do I need one turn to activate this ability and then another turn to use one discipline, etc. until I finish this pool? Finally, Disciplines are a block of several options, what does it mean when I choose to use these bonus points; is the entire block unaccessible with regular psi points?