I think that's pretty much the defining line in the film.
Harold and the rest of us all fall in love with Maude because she is utterly free and whole. Maude is free and whole because she loves without fear or hesitation, vigorously and zestily. Witness how she expresses her love of a tree, making no consession to consequences. An ultimate consequence of love is loss and the fear of this pain is the reason most people do not love as Maude does and cannot be free. To be free one must accept loss, accept that the loss of a loved thing does not make one less whole or less able to go out and love some more. When you can absorb that and live in that truth, you can destroy your cute Jaguar hearse (and other attempts at 'self-expression' that are really about controlling how people react to you) and take up the banjo (an excellent symbol for Maude-like personal freedom, it's a lot of fun, but no matter how good you are people will laugh at your banjo-playing.)