You can do this:

use Data::Dumper;

 my @a_array = ('apple 2', 'orange 5', 'pear 3',);
 my @b_array = ('apple', 'apple', 'apple', 'orange', 'orange', 'pear',
+);

 my @c_array; 

  for my $item_1 (@b_array){
    for my $item_2 (@a_array){
      push @c_array, $item_2 if $item_2=~/^$item_1/;
    }
  }

 print Dumper \@c_array;
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$VAR1 = [
          'apple 2',
          'apple 2',
          'apple 2',
          'orange 5',
          'orange 5',
          'pear 3'
        ];
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