"The Rookie" is a police procedural crime drama television series created by Alexi Hawley for ABC). The series follows John Nolan, a man in his forties, who becomes the oldest rookie at the Los Angeles Police Department (LAPD)). The show has been reviewed by Common Sense Media, where it is described as a police show with a lot of violence depicted, including murders and shootouts. The show concentrates on depicting ways in which police officers must behave differently from civilians -- things like following orders, handling weapons, and how to cope with things that happen on the job -- and when it may or may not be appropriate to break protocol in order to help people.
There is no official rating for "The Rookie" as it is a TV show and not a movie. However, Common Sense Media has rated it as appropriate for ages 16 and up due to its graphic violence and mature themes.