The Pufferfish Trap is used to catch the mobs and burn them in the lava.
This guide will let you know how to make a Pufferfish Trap in the Minecraft game.
The first thing you have to do is to remove grass from two layers of 5 blocks and then add pistons in the back layer and smooth quartz block in the front gap.
The next thing you need to do is to place the pistons and smooth quartz blocks by leaving a gap of 2 blocks on the right.
Dig the center area up to 3 blocks and add lava buckets in it. Use red stone dust on the outer sides of the pistons and place a redstone torch on the ground as shown in the image below. This will push the pistons forward.
Make a wall of smooth quartz blocks on all sides and roof of the door in the same way as shown in the following image.