my @arr;  # no need to initialize (and in any case, "= ''" makes little sense)
my @hdr;
open( F, "x.txt" ) or die $!;
while (<F>) {
    chomp;
    my @flds = split /,/;
    push @array, join( ' ', @flds );
    push @hdr, $flds[1];
}
print join( '/', @hdr ), "\n";
print join( "\n", @array ), "\n";