Okay kiddo, so there was a person named Rinaldo who did something that broke the rules that the government made up. This means that the government (or the state) believed that Rinaldo broke their rules and they wanted to punish him for it.
To decide if Rinaldo did break the rules or not, the government had a trial where they looked at all the evidence and heard from different people. This trial is called State v. Rinaldo.
During the trial, Rinaldo had a lawyer who tried to prove that Rinaldo didn't break any rules and that he was innocent. But the government had their own lawyer who tried to prove that Rinaldo was guilty and should be punished.
In the end, the judge or the person in charge of the trial had to decide if Rinaldo was guilty or not. If he was found guilty, he would be punished for breaking the rules. If he was found innocent, he wouldn't be punished and could go back to his normal life.
So State v. Rinaldo is just a fancy way of saying that the government accused Rinaldo of breaking their rules and they had a trial to decide what should happen to him.