plotDiagnostics leverage how does it work

Hey! I have just the plotDiagnostics function (Statistics toolbox) and was wondering what the leverage on the Y means exactly? I found this: The leverage of observation i is the value of the ith diagonal term, hii, of the hat matrix H. Because the sum of the leverage values is p (the number of coefficients in the regression model), an observation i can be considered to be an outlier if its leverage substantially exceeds p/n, where n is the number of observations. But not quite sure what it means.. Can someone explain me it, maybe in easy words? What I understand is that a higher leverage has a higher influence on the model,right? Thank you!