EndPackage[ ] restores $Context and $ContextPath to their values before the preceding BeginPackage, and prepends the current context to the list $ContextPath.
Every call to EndPackage must be balanced by an earlier call to BeginPackage.
EndPackage is typically used at the end of a Mathematica package.
EndPackage returns Null.
EndPackage resets the values of both $Context and $ContextPath.
See The Mathematica Book: Section 2.6.10.