Evidence that irrefutably proves something is very strong evidence.
Evidence that kind of points towards something, but inconclusively, is weak evidence.
For example, if 100 witnesses saw the accused murder the victim, and they're all credible, and they tell corroborating stories, that's pretty strong evidence.
If 1 person thinks he saw the accused murder the victim, from the other side of a car park, but he has bad eyesight anyway and it was dark and raining, then that's weak evidence. It's not nothing, it's still evidence, but it is weak.
Evidence that kind of points towards something, but inconclusively, is weak evidence.
For example, if 100 witnesses saw the accused murder the victim, and they're all credible, and they tell corroborating stories, that's pretty strong evidence.
If 1 person thinks he saw the accused murder the victim, from the other side of a car park, but he has bad eyesight anyway and it was dark and raining, then that's weak evidence. It's not nothing, it's still evidence, but it is weak.