If you have to ask a pop filter is a noise protection filter or a shield for microphones. They help reduce the popping sound made of fast moving air through your microphone. Essentially when we are listening to your favorite artist that is what makes the sound almost flawless, well besides talent and mixing skills a lot of this is because of the use of a pop filter.
Here are a few more things you need to know about a pop filter. A pop filter is composed one or maybe more layers of semi-transparent material like metallic mesh or nylon.