Well, there is no consensual definition of Forensic Psychology, the definition ranges from expansive ones (that include application of psychology to legal systems) to narrower ones (limited to clinical and counselling psychologists).
The American Psychological Association (APA) in 2013 has defined forensic psychology as the "professional practice by any psychologist working within sub-disciplines of psychology (clinical, developmental, social, cognitive) when applying the scientific, technical or specialized knowledge of psychology to assist the law in addressing legal, contractual and administrative matters."
The American Board of Forensic Psychology defined it as " the application of science and profession of psychology to questions and issues relating to law and legal systems."
yes it is.
I think in simple words its basically psychology combined with legal- law and criminal matters.