Okay kiddo, probative is a big word that means something helps to prove or show something else.
For example, imagine you're trying to convince your friend that you're really good at basketball. You might show them your basketball skills by dribbling, shooting the ball, or showing them a video of you playing in a game. All of these things are probative - they help to prove that you're good at basketball.
In a court of law, probative evidence is the type of evidence that helps to prove or disprove something. For example, if someone is accused of stealing something, probative evidence might include fingerprints found on the stolen item, eyewitness testimony, or surveillance footage of the person taking the item. All of these things could help prove whether or not the person actually stole the item.
So, probative evidence is basically any evidence that helps to prove or disprove something in a court case or argument. Pretty cool, huh?