The term "probative" in evidence law refers to anything that tends to prove something. This is the reason why testimony that doesn’t prove anything is considered inadmissible or immaterial in the eyes of law. Such testimony is removed from the record if the opposing party objects.
For evidence to be probative, it is necessary that it proves an issue or a fact, or that helps in doing so.
Probative facts or evidence sometimes play their part in the establishment of other facts, which aid the court in making a just decision.