Just as the motor hand can set a string in motion (pick/pluck), the fretting hand can do the same. These are called slurs. Slurs can be indicated with a curved line...
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Slurs mean to connect tones smoothly [legato]. We fret & pick the the higher tone, then 'pluck' with the fretting hand to sound the lower.
Fret the 2nd fret on the 1st string, pick the 2, then use the fretting hand to ‘pluck’ to the open.
If pulling to a fretted tone, we fret that tone at the same time that we fret the tone that we are going to pick.
The motion of the pull can be from the finger or arm, or most commonly, a combination.