Your Module.pm doesn't set up a separate namespace from which functions may be imported by another package. All your functions are compiled into the caller's namespace:

Extending your Module.pm functions slightly

require Exporter;
@ISA = qw(Exporter);

@EXPORT =qw\fun1 fun2\;

@EXPORT_OK = qw\fun3\;

@EXPORT_FAIL= qw\fun4\;

sub fun1{print "\nfun1 in package " . __PACKAGE__ }
sub fun2{print "\nfun2 in package " . __PACKAGE__ }
sub fun3{print "\nfun3 in package " . __PACKAGE__ }
sub fun4{print "\nfun4 in package " . __PACKAGE__ }
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the script

use Module;
fun1;
fun2;
fun3;
fun4;
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outputs

fun1 in package main
fun2 in package main
fun3 in package main
fun4 in package main
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Nothing exported, nothing imported. All is in the default package 'main'.

Use a package statement in your Module.pm:

package Module;
require Exporter;
@ISA = qw(Exporter);
...
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Running the script again yields

fun1 in package Module
fun2 in package Module
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