Alright kiddo, have you ever played with Legos before? Imagine if you were building a tower, and you had lots of flat Lego pieces that you wanted to use to build the sides of your tower. But instead of grabbing each piece one at a time, you could grab a bunch of them at once and snap them together all in one big row.
That's kinda like what a triangle strip is in 3D computer graphics. A triangle strip is a group of triangles that are all connected to each other, like a long zigzag. Instead of drawing each triangle one at a time, the computer can draw them all together in a single strip. This saves time and makes everything run smoother.
So imagine you're playing a video game and your character is running through a field. The grass in the field is made up of lots and lots of tiny triangles that the computer draws really fast so you can see the grass moving as you run. But instead of drawing each triangle one at a time, the computer can draw them all in one long triangle strip. That makes the grass look smoother and more realistic as you run through it.
Does that make sense, kiddo?