> please explain in simple way

Can't be simpler! Just write a parser for the input format.

#!/usr/bin/perl

# http://perlmonks.org/?node_id=1173242

use strict;
use warnings;

my @header;

while(<DATA>)
  {
  local $" = ':';
  1 while
    /\G\s*(\w+)\)/gc   ? push @header, $1 :  # name)
    /\G\s*(\w+=\S+)/gc ? print "@header: $1\n" :  # parameter=value
    /\G\s*;;/gc        && (pop @header, @header || print "\n");  # end
  }

__DATA__

 abhi)
       old_file="ak.csv"
        datefile="ak_nt_$curr_date.csv"
       cat /aksin/nil; cat /home/null
      
     case `kumar` in
       dbk)
           newwack="rac_client_$curr_date.ack"
           IN_DIR="class/5060"
       ;;
      src) 
          src_folder="class/5061
        ;;
    esac
       echo "$date_file"
   ;;

  bill)old_file="abh_cash.csv"
       date_file="ods_nt_cash_acc_$curr_date.csv"
       newwack="rac_cash_acc_$curr_date.ack"
       IN_DIR="xyx\5060"
   ;;

payu)
      old_file="ods_ven.csv"
     newfile="ods_nt_ven_$curr_date.csv"
     newwack="rac_vendor_$curr_date.ack"
     IN_DIR="ofc\5060"

    case para in
       bcc)
           newreck="client_$curr_simul.ack"
           IN_DIR="class/5062"
       ;;
      src1) 
          src_folder="class/5061
        ;;
    esac
     ;;
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