Snapchat Geofilter are special overlays for Snaps that can only be accessed in certain locations. So, basically, they are pretty graphics that dress up a Snap. They're very similar to digital stickers, except they are actually built into the program. Geofilters change depending on where someone is when they take a photo or video.
Here some Geofilter design by me for different locations.
My Snapchat profile: https://www.snapchat.com/add/saqib_m55?share_id=NTAwQTUy&locale=en_US