Sure! It's pretty trivial. I'm going to assume at least a high-school knowledge of math, since I'm assuming you're unfamiliar with terms like bimodal distribution, categorical data, et cetera. If you're interested in learning more, this kind of thing generally falls under statistics.

So this boils down to the question of essentially "if everything is on a spectrum, how can we categorize it?" and the answer basically boils down to "it's arbitrary." This is essentially called analog-to-discrete conversion. To skip ahead, human sex is on what's called a bimodal distribution. That means there's two big bumps on either end of the spectrum, and very little in the middle, but it's still accepted to be a spectrum. We can just "summarize" it by sorting them into discrete categories. Let's use voltage as an example! Common voltages have 0V for "False" and 1V for "True," right? For discrete signals. But what if the voltage is .3V? If the exact voltage isn't important, we can "summarize" it by setting an arbitrary limit (generally .5V), and then anything below gets summarized to 0V or "False," and anything over or including .5 V gets sorted into 1V or "True," but it's important to note that this has NOTHING to do with the underlying voltage we are measuring. The limit is arbitrary and we're only doing it because the exact measurement in this particular case isn't that important. Science is like this in general: we have the data that we don't understand, and we try to categorize it to make sense of it. But this obviously fundamentally doesn't change whatever we are actually measuring, this is just how we are defining and categorizing that information.

We don't have to imagine other forms of sexually reproducing species; we have many, many, many other examples across life, insects, mammals, bacteria all have different ways of combining genetics and reproducing. Clown fish are pretty much all hermaphrodites and can switch genders under stress, and this isn't that uncommon. There are plenty of examples of intersex individuals who can still reproduce, and plenty who can't for a variety of reasons. Humans are one of the few species that go through menopause, for example. The general idea for this two is talking about general reproductive strategies (for example, XY chromosomes etc etc) is different from talking about an individual, which might be sterile, intersex, whatever. This also is where societal roles come into play et cetera. This is a much larger discussion, though, and it would be difficult for me to summarize here, but I hope I've at least given you some terms so you can understand what's happening. Basically what science does is work from a bottom up approach: we have a lot of data, and we try to understand what is going on by applying labels and seeing if that helps, but these labels and limits are all changing and arbitrary, it doesn't actually affect what we're measuring. We try to use words to describe biology, we can't use words to influence biology, if that makes sense. A statistics class would probably help describe this better.