This summary is not the rule. The rule text controls.
Evidence counts as "relevant" if it helps prove or disprove something that matters in the case. The evidence does not have to fully prove a fact by itself. It just needs to make a fact seem a little more likely or a little less likely to be true.
For example, if someone is on trial for theft, evidence that they needed money badly at the time does not prove they stole anything. But it makes the idea that they might have stolen something slightly more believable, so it would count as relevant. The bar for relevance is low. Evidence just needs some logical connection to a fact that matters in the case, even if that connection is small.
Courts use this rule as a first filter. If evidence has no connection at all to any fact that matters, it gets left out. If it does have some connection, it can move on to other rules that decide whether it should still be allowed in court.
