See the current Perl documentation for import.
Here is our local, out-dated (pre-5.6) version:
import - patch a module's namespace into your own
There is no builtin import() function. It is just an ordinary method (subroutine) defined (or inherited) by modules that wish to export names to another module. The use() function calls the import() method for the package used. See also use(), the perlmod manpage, and the Exporter manpage.