Yes and No.
If you have Windows Server then SharePoint Foundation Include in it. SharePoint Foundation is free /lite version of SharePoint server.
SharePoint Foundation 2010 is a versatile technology that organizations and business units of all sizes can use to increase the efficiency of business processes and improve team productivity. With tools for collaboration that help people stay connected across organizational and geographic boundaries, SharePoint Foundation 2010 gives people access to information they need.
SharePoint Foundation 2010 and One more thing SharePoint Foundation license is covered under the Windows Server Cal, that's mean if a user covered under the Windows Server then he covered under SPF.
SharePoint Server 2010. Microsoft SharePoint Server 2010 is the business collaboration platform for the enterprise. Use SharePoint Server 2010 to connect people with colleagues and information; manage and govern enterprise content; balance user experience with policy and process; and help users find the content, information, and people they need with enterprise search.
SharePoint Server product, you have to buy separate license according to your need either Standard & Enterprise.