This bonus appears at random. There is no other way to trigger its appearance.
When a card displays this symbol above it, it indicates that at the end of the round, a lightning strike will hit the timer. This bonus adds extra time and moves the timer back, keeping you in the game for longer.
Lightning strikes can be stacked. If you collect multiple cards displaying the lightning strike symbol in a round, each one will activate at the end. For example, if you gather four of these cards, four lightning strikes will hit the timer, adding even more time and pushing the progress bar back further.

No.