Why does a manager need to share the objectives of the company with their employees?
Either deliberately or inadvertently, many managers with an authoritarian style of leadership and management will run their company or specific department on a 'need to know' basis, insofar as they will not share with their employees the desired goals or current status of the business. These managers will feel that workers should just 'get on with their particular job' and not worry about anything else other than producing whatever it is they are employed to do.
However, this rather old-fashioned way of thinking can lead to problems, or at the very least greatly inhibits the potential of the manager's team. Employees who have the company's aims shared with them are usually more likely to push themselves to achieve them. It is human nature to want to see some results for the hard work put in. Nobody wants to slog away and feel like they are getting nowhere, but if they can see that progress is being made, even if it is only slight, they will be much more motivated to carry on with what they are doing. So for example if your sales team has been tasked with selling more to improve the company's sales figures and they have, share those figures with them. It will also reaffirm for them that what they are doing is achieving the right results so they will carry on, rather than changing tactics which may then undo or reverse all the gains they have just previously made.
A combination of experience and management training courses will allow a manager to develop their people skills and motivational techniques to get the best out of their employees.