Sassarese is a way of talking that some people in a small city called Sassari in Italy use. It's kind of like how you talk to your friends and family - you might use different words or say things in a certain way that you wouldn't use with strangers or in school.
Sassarese has some special words and sounds that are different than other languages in Italy. For example, the sound "ch" is used a lot, like in the word "ciao" which means hello. In Sassarese, it might be said more like "ciacho!"
People who speak Sassarese also have a strong accent, where they might draw out certain sounds or not pronounce other sounds all the way. It might sound funny to someone who isn't used to hearing it!
But even though Sassarese is a different way of talking, people in Italy still understand it and think it's important to keep their special language and culture alive.