Hey there! A non-conventional trademark is a fancy way of describing a type of trademark that isn't exactly like a typical one. Usually, when we talk about trademarks, we think of things like logos or brand names. Those are the usual, conventional way of putting a trademark on your product or service. But sometimes, people or businesses might want to use something different to trademark their stuff, like a sound, a color, or even a shape.
Let me give you an example: you know how you can tell when you hear the "ding" sound on an iPhone that you've just received a message? That sound is actually a non-conventional trademark. Apple, the company that makes iPhones, decided that they wanted people to associate that "ding" sound with their brand, so they registered it as a trademark. That means that no other company can use that sound in the same way without getting in trouble.
Another example of a non-conventional trademark is the Coca-Cola bottle shape. You know how Coke bottles are curvy and have a little dip in the middle? That shape is trademarked, too. If another company tried to sell their soda in a bottle that looks exactly like a Coke bottle, they could get sued for using someone else's trademark.
So, basically, a non-conventional trademark is just a type of trademark that uses something other than a logo or brand name to identify a product or service. It's a way for companies to protect their unique features and make sure that nobody else can copy them.