Phrasing on the guitar is somewhat complicated by the fact that how something gets phrased is a combination of where you play it on the guitar; slurring, which you can only do on one string; and picking. And these three things are blurred into one another. It’s not like a saxophone where the phrasing is done with the mouth and the fingering is done with the fingers.
We have one hand picking, one hand fretting, slurring has to happen on one string.
Anyway, to be good at it, you need control of the various things you can do. So to control the picking, you need to be able to pick well and with a good sound, as well as being able to control the dynamics. That’s what this exercise is about. It uses extreme accents; the quietest note you can make, and the loudest. Accent them as suggested.
There are various ways of getting a loud note. If you hack across the string so it snaps, the vibration somehow cancels out the volume/fullness of the tone. So try putting a lot of pick on the string, dig deep into the guitar, and pull the pick directly out, sort of the opposite of a classical rest-stroke. Eric Johnson and Clapton do this. It’s a good way to get a loud accent. Make the quiet note as quiet as you can but positive; don’t whimper away.
After you’ve played the exercise starting on a downstroke, do it again but start on an upstroke.