>Giulia: Hop on. I could use the extra weight.
What does she exactly mean by: "I could use the extra weight."? What is she referring to? Could you please paraphrase it?
Giulia is talking to Ercole who is teasing Giulia for not succeeding in the race last year. Giulia is defending Luca and Alberto (to whom she says: Hop on!) and taking them (who are being harassed by Ercole) with her. Giulia just met Alerto and Luca.
Hope this will help.