What it includes
A value proposition answers the buyer's question: why should I care? A useful one names a specific customer, a problem they recognize, the outcome you deliver and what makes your approach different from the alternatives, including doing nothing. It isn't a slogan or a feature list. Marketing usually writes the company-wide version; reps need to translate it for each buyer, because a finance leader and a team lead value different outcomes from the same product.
Example
A generic version reads: 'Our platform streamlines invoice processing.' A buyer-specific version says: 'For finance teams whose month-end close runs late because invoices are keyed in by hand, we automate the data entry so the close stops slipping.'
Why it matters
Without a clear value proposition, reps describe features and hope the buyer connects them to a problem. Most buyers won't do that work. A sharp value proposition gives every conversation a center: the opener, the discovery questions, the demo and the proposal all point at the same outcome. It also helps in competitive deals, where the buyer has to explain to colleagues why one option is better. If they can repeat your value proposition in one sentence, you've given them that explanation.
How to make it yours
Practice saying your value proposition for each type of buyer in one or two sentences, in plain words. Test it in discovery by asking whether the problem it describes is real for this buyer, and adjust when it isn't. In practice calls, notice when you slip into listing features. A useful check is to finish each feature you mention with 'which means you can...' and see whether the ending matters to the person you're talking to.