Intercalary month (Egypt)

Okay kiddo, do you know how we have 12 months in a year? Well, the Ancient Egyptians used to have 12 months too, just like us. But they noticed that their seasons were changing and the river Nile's water level was not staying the same each year like they thought it would. So they decided to add an extra month into their calendar every few years to make sure their seasons were in the right order. This is called an 'intercalary month', which means a month added in between the others, kind of like a bonus month. It's like an extra present you get sometimes, just to make sure everything stays the way it should. Egyptians used to call this month "Mesori". So, when they added this intercalary month to their calendar, they now had 13 months instead of 12. Does that make sense, kiddo?