Okay kiddo, so colors come in different shades and we can use numbers to describe them. The RGBA color model is a way to describe colors using four numbers: red, green, blue, and alpha.
Red, green, and blue are the primary colors that make up all other colors. Alpha refers to the transparency of the color. So, if a color has a high alpha value, it's more transparent, like a see-through glass. If it has a low value, it's more opaque, like a solid object.
So when we use the RGBA color model, we put these four numbers together to make our desired color. Let's say we wanted a light blue color that's pretty opaque. We could use the numbers rgba(135, 206, 235, 0.8). The first three numbers (135, 206, 235) describe the red, green, and blue values, while the last number (0.8) describes the alpha value, or transparency.
That's how we use the RGBA color model to create and describe different colors. Cool, right?