A sandbox is a restricted execution environment that enables programs to access only certain resources, and causes problems that occur in the sandbox to not affect the rest of the server environment. Solutions that are deployed to the sandbox are called sandboxed solutions that do not use certain computers and network resources or access content other than the site collection they are deployed to.
Enable sandboxed solutions on a server farm
Because sandboxed solutions do not affect the entire server farm, you do not have to be deployed by the server farm administrator. If a sandboxed solution is enabled on any server in the server farm, the site collection administrator can deploy the solution to a run in the sandbox.
Ways to enable sandboxed solutions:
1, use the central administration to enable snakes and solutions
1.1. Confirms that the current user is a member of the Farm Administrators group;
1.2. "Central Administration"-"System Settings"-"Managing services on a server"
1.3. In the Server box, select the server on which you want to enable the sandboxed solution.
1.4. In the Microsoft SharePoint Foundation Code Services line, click Start in the Action column.
1.5. Repeat the previous two steps for each server on which you want to enable sandboxed solutions.
2. Enable sandbox solution with Windows PowerShell
Start-service-name SPUserCodeV4