No worries at all, the game is definitely a little esoteric. The green bar represents the cattle-stunner being charged. Each time you play a word from your word inventory, the stunner charge bar goes up 1. There are 15 bars, e.g., you have 15 "turns" to try and escape. So you want to escape before the bar fills up!
I also added a replay button at the end, after much feedback, if that helps.