The rolling "r" sound is a big component in various languages, like Spanish.
It can be tricky! A lot of people who don't learn how to do this in childhood can have trouble with it later on in life.
In a nutshell, you place your tongue near the roof of your mouth, curl it, and blow a stream of air out over it, making the tip of your tongue vibrate.
Let's test it out.
We'll start with an easy one. Can you pronounce "perro"?