Alright kiddo, imagine you're at a big birthday party with lots and lots of other kids. There's so many people that you don't even know most of them. That's kind of what we mean when we talk about mass society - it's a really big group of people that don't know each other personally.
In the olden days, people lived in small communities where everyone knew each other's names and what they were up to. But as time went by and technology got better, people started moving to cities and towns, and they began to live alongside people they didn't know. This was the start of mass society.
In a mass society, there can be positives and negatives. On one hand, it means that we have access to a lot more resources and opportunities than we used to. We can learn from people all over the world because we have things like the internet and TV. But on the other hand, it can also make us feel a bit disconnected from each other. It's hard to feel like you're part of a close-knit community when there are so many people around.
Overall, mass society just means that we're part of a really big group of people that we don't necessarily know very well. It has its benefits and drawbacks, but it's just a fact of modern life.