In common use, cropping up in many conversations, it is used to refer to actions or activities which 'increase shareholder value' - ie, it benefits the financial interests of the shareholders and will ultimately increase the value of any shares that investors may hold. Delivering proposals to customers with proper financial appraisal can only help improve this 'shareholder value'.
Oh, the very pinnacle of Corporate speak! Almost seems you are a Board member already. This is a term used by Boards to justify their activities, strategies, and investment decisions. It's the basic requirement to deliver value to shareholders - commonly through higher share prices, better profits, or sound investment. It's what Boards of Directors are hired to deliver.