Turn on your pressure cooker to the sauté function. Throw in the bacon and cook up for a few minutes. It doesn't need to be very crispy since it will soften up when cooked with the beans.
Add the green beans, diced onion, garlic, chicken broth, butter, and sprinkle with salt and pepper.
Give it a stir.
Put on the lid, seal, and make sure the vent is shut. Set to pressure cook for 12 minutes. This will make the beans very soft. If you would like them a little more firm, start with 6-8 minutes.
When the timer goes off, let the pressure cooker release on its own for a few minutes, and then you can do a quick release if wanted.