Okay kiddo, have you ever looked at a clock and seen numbers like 1, 2, 3, all the way up to 12, and then you see those same numbers again but this time there is a little dot and another number after it like 1:00 or 2:30? That's what we call a 12-hour clock!
So, when we use the 12-hour clock we are showing the time of day from midnight to noon and then from noon to midnight again. It's called the 12-hour clock because we only use the numbers 1-12 and repeat them twice in a day.
But you might be wondering, "Why do we only use 12 hours? Why not use all the numbers on the clock?" Well, it's because the 12-hour clock was used a long time ago when it was hard to keep track of time during the night. So, people would divide the day into two parts, one from sunrise to sunset and the other from sunset to sunrise, and they would use the 12-hour clock to measure time during these parts of the day.
Nowadays, we use digital clocks that can show us the time in the 12-hour format or in the 24-hour format (which uses all 24 numbers on the clock to show the time) but the 12-hour clock is still used in many parts of the world.
So, there you have it kiddo, the 12-hour clock is just a way of measuring time using only the numbers 1-12 and it helps us keep track of time during the day and night!