There are two kinds of evidence, direct evidence and circumstantial evidence. Direct evidence is something that does not need to be interpreted or thought about. It directly proves a claim. By contrast, circumstantial evidence does need to be interpreted.
For example, let us say that someone has been murdered by stabbing. In this case, direct evidence would be some sort of evidence that unequivocally shows that the suspect stabbed the victim. There could be eyewitness evidence from someone who actually saw the stabbing occur. There could be video evidence from surveillance cameras.
There could also be many kinds of circumstantial evidence in this case. For example, a witness could have seen the suspect come out of the dead person’s apartment carrying a knife that was dripping with blood. The coroner could testify that the stab wounds to the victim were made with a knife of the same general size and shape that the defendant was carrying. These types of evidence are not direct because they do not directly show the suspect stabbing the victim. However, they can be quite persuasive, particularly when there are many pieces of such evidence.