Bimodality means having two big humps. Imagine a valley with two big mountains on either side. The valley has a peak in the middle and then goes down to the two mountains. This is called bimodal because there are two big mountains on either side of the peak.
In math, bimodality means that there are two different groups of numbers that are both really big, and they have a big gap in the middle. For example, imagine a class of students taking a test. Some students do really well, and some do really poorly. There might not be many students in the middle who did just okay. Instead, there are two big groups, one with high scores and one with low scores, and not many in between.
Bimodality is important to know about because it can affect the way we understand and analyze data. If we only look at the average (the middle), we might miss important information about the two big groups of numbers on either side. By understanding bimodality, we can make sure we are looking at all the important parts of the data.