A subroutine gets it's arguments as an array (@_), so if you do

my @array = (1,2,3,4,5);
some_sub(@array);
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Within some_sub, @_ will equal the contents of @array.
However, you probably want to pass the array into the subroutine by reference (see perlref for more):

my @array = (1,2,3,4,5);
some_sub( \@array );
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In that case, the first element of @_, the argument list to some_sub, will be a reference to @array.