The Dumpster Fire marks the end of the Episode, and gives bonus rewards. When you have completed the minimum amount of required goals, clicking on the Dumpster Fire in the top right allows you to put out the fire.
To put out a Dumpster Fire, tap on the Dumpster repeatedly. Each time you put out a Dumpster Fire, you will receive rewards.
What is Trash Power?
Trash Power is how you can increase the rewards from putting out the Dumpster Fire. Upgrading Frank cards increases your Trash Power, which then increases your rewards at the end of the Episode.
Each time you level up Frank, you add a bit more to your Trash Power. Once you accumulate enough upgrades, you increase your Trash Power which increases rewards.