Steve vai 30 hour workout help!
 

Need help with understanding some of the exercises:




And what does it mean to "play an interval"?Is it playing two chords that are connected in the circle of fifths?

A minor second is an interval of 2 notes a half step apart. (C and B for example)

And for your second question.... do you understand music theory? Because it sounds like you're confused about something quite simple....

An interval is just the distance between notes, or in other words a description of how many steps or halfsteps there are between notes. What he means in this excerpt is that when you play a line on the guitar try to sing a note that is a certain distance away from the note you are playing. In the case of the fifth, when you play a note, sing the fifth which is the second note of a power chord. Then when you can do that try to sing a fourth along with what you're playing, and continue working on it til you can harmonize any note you play with any other note using your voice.

A minor second is a half-step, so he means that when you play a note, try to sing the note that is one fret up from it.

I do this workout each weekend and about that it says that it's difficult. So I'd suggest starting with the simpler aural training. Btw, study the theory it says to do so.