Mac Fhirbhisigh is a very old Irish name that belonged to a man who lived a long time ago. He was a historian and he likes to write down stories and information about his country and the people who lived there. Think of him like a really smart person who knows a lot about Irish history.
His name is kind of funny to say though, right? Mac Fhirbhisigh is pronounced like "Mack-Feer-Vi-Sig". It's a pretty long and tricky name to say! But he must have been a very important person because people still know about him and his work today.