Hybrid cloud environments exist where private and public services are used together to create flexibility and value. A hybrid cloud scenario enables organizations to have traditional on-premises resources, resources in a private cloud, and resources in the public cloud, simultaneously. The hybrid cloud model allows you to take advantage of the strengths of each platform.
For a more in-depth definitions, see the description of hybrid cloud from Margaret Rouse on TechTarget or What is Hybrid Cloud Computing?
SQL Server 2014, in particular, uses a familiar of tools to deploy and manage databases both on-premises and in the cloud, which makes it easier to take advantage of the cloud with existing skills and resources.