use Data::Dumper;

# everything is fine using this @taulell array
#@taulell = ( ['B1','B2','B3'], ['B4','B5','Y1'] );

# here is how you set @taulell
sub inicialitzacions
{
    $torn='B';
    @{$taulell[3]}[3,4]=qw(B N);
    @{$taulell[4]}[3,4]=qw(N B);
    @pos{'x','y'}=(2,2);
}
inicialitzacions();

# @taulell looks like this
print Dumper(\@taulell);

my $num=0;

for(@taulell)
{
    $num+=grep /B/,@$_;
} 

# @taulell now looks like this
print Dumper(\@taulell);

addstr(2,1,"B = $num");
addstr(24,3, "Y = $pos{y}");
$num=0;

map 
{
    $num+=grep /B/,@$_;
} @taulell;      
addstr(3,1,"N = $num");
addstr(24,35,"Tecla = <$key> ");

# @taulell now looks like this
print Dumper(\@taulell);

sub addstr {}