Rota fortunae is a fancy way of saying "the wheel of fortune". Imagine a really big wheel that has different pictures and words on each section of it. This big wheel spins and spins, and wherever it stops is what you get.
The idea of rota fortunae is that life is kind of like that wheel. You can't always control what happens to you, and sometimes good things happen and sometimes not-so-good things happen. Just like the wheel spins and you never know where it will stop, life is also a bit of a surprise sometimes.
This idea has been around for a very long time and was even talked about by ancient philosophers like Plato and Aristotle. They believed that the wheel of fortune represented how life was full of ups and downs and to be happy, you had to make the most of the good times and keep going through the bad times.
So, in short, rota fortunae is just a way of explaining that life can be unpredictable, and we just have to learn how to deal with whatever it throws our way.