This summary is not the rule. The rule text controls.
Witnesses, including experts, can give opinions that touch on the main question the judge or jury has to decide in a case. In the past, some courts blocked this kind of testimony because they thought it stepped on the jury's job. This rule says that's not a valid reason to keep the opinion out.
So if an expert believes a car was going 60 miles per hour, and speed is exactly what the case is about, the expert can still say so. The jury doesn't have to accept that opinion. They can weigh it along with everything else and decide for themselves what really happened. The rule just makes sure useful opinions aren't automatically thrown out just because they get close to the heart of the case.
