"Ella ha presentado su idea."
Translation:She has presented her idea.
"She has presented her idea." "She has presented your idea."
I work in an agency where it's important to be able to say both of these things. How would you distinguish between the two in Spanish?
People here usually say that the conversational context will make it clear. And with "she" as the subject, "her idea" is probably assumed, or perhaps you could use something like "su propia idea" (her own idea).
However, the grammatical pattern for clarifying possessive adjectives is def. art. + noun + de + pron. So, her idea = la idea de ella; your (singular) idea = la idea de usted; your (plural) idea = la idea de ustedes.
"Su idea" could also mean his idea (la idea de él) and their idea (la idea de ellos/as).
That's super common. The h is silent so 'ha' gets swallowed pretty hard if there's an a before it.