Hey there kiddo! So, a long time ago in Ireland, there were two main groups of people - the Protestants and the Catholics. The Protestants were a group of people who believed in their own version of Christianity, and the Catholics believed in a different version.
Now, the Protestants were very powerful in Ireland and had a lot of control over the government and the land. This is called the "Protestant Ascendancy." It meant that the Protestants were seen as more important and powerful than the Catholics. The Protestants had more money, better jobs, and more opportunities.
The Catholics didn't like this very much, because they felt like they weren't being treated fairly. They didn't have the same rights or opportunities as the Protestants did. They wanted things to change so that they could have more power and control over their lives.
Eventually, there were protests and demonstrations by the Catholics to try and change things. They wanted more equality and fairness. It took a long time, but eventually things did start to change and the power of the Protestant Ascendancy began to fade.
Today, Ireland is a much more equal society where people of different religions and backgrounds have the same rights and opportunities. So, that's what the Protestant Ascendancy was all about - a time when one group of people had more power and control than another, but eventually things changed for the better.