Okay kiddo, so you know how sometimes when we are trying to say a word, we accidentally pronounce it differently than it should be? That's basically what "dissimilation" means!
When we speak, we use our mouth, tongue, throat, and other parts of our body to create different sounds. Sometimes, these sounds can be hard to make or it can be difficult to say them in sequence without making a mistake.
So, when we say a word with two of the same sounds close together, it can be hard for our mouth to make both sounds separately. That's where dissimilation comes in.
Dissimilation is when we change one of the sounds in a word so that we don't have to say two of the same sound next to each other. For example, it's easier for our mouth to say "com-fort-able" instead of "com-for-table".
Dissimilation is a natural part of language evolution, meaning that it happens over time as languages are spoken more and more. It can also help people to communicate more easily and efficiently.