Okay kiddo, imagine you are standing with your arms stretched out in front of you. When you point your right hand in front of you and then your left hand, you notice they are pointing in opposite directions, right? That's because they are pointing along different sides of your body. But if you put a mirror in front of you, then the image you see will look like your right hand is pointing to the left, and your left hand is pointing to the right, even though in reality they are still pointing in the same direction as before.
This is kind of like what a pseudovector is. It's a vector that, even though it points in a particular direction, looks like it's pointing in the opposite direction when reflected in a mirror. This happens when the vector is formed by two or more other vectors that are not aligned, but instead are "twisted" around each other.
Pseudovectors are important in physics because they are involved in many phenomena where symmetry plays a big role, like in electromagnetism, where they can affect how electric and magnetic fields interact in certain situations. So, even though they might seem a bit tricky to understand since they can be affected by reflections, they are actually very useful in helping scientists understand how things work in the world around us.