Imagine you have a pet dog named Max. Sometimes, Max does things you do not like, like jumping on you or taking things that are not his. You want Max to know that those things are not okay, so you might decide to "alpha roll" him.
An alpha roll means you flip Max onto his back and hold him there until he stops struggling. You might also stare into his eyes to show him you are the boss. In the wild, this is what alpha wolves do to subordinate pack members to show dominance.
However, alpha rolling can be confusing and scary for Max. It can also be dangerous, as he might try to defend himself if he feels threatened. There are better ways to train a dog, such as positive reinforcement and offering treats when he does something you like. So, it's probably best not to alpha roll Max or any other dog.