Squiggly Lines
[Classical Music Mode On]
Arpeggio is a musical technique where notes in a chord are played or sung in sequence, one after the other, rather than ringing out simultaneously.
[Classic Music Mode Off]
The 'squiggly line' indicate that it is played 'arpeggio' rather than a quick strum. You can pick the notes, but I actually find that strumming the chord slowly and deliberately one note at a time with the fleshy side of the thumb or the index finger, depending on the direction of the arrow, works really well and is much easier than plucking. The technique fills in the sound nicely.
Note that the direction of the arrow is important!
An alternative is to simply pluck the last note (top or bottom) at that point.
Look up "Solobuch" and you will find it full of song based entirely on this technique. I hope to get a couple of songs recorded and up on YouTube in the next month.