use strict;

# I'm assuming I'm getting @data from some file.
use IO::File;

my $fh = IO::File->new('Some_filename')
    || die "Cannot open 'Some_filename' for reading\n";

my @data = <$fh>;

$fh->close;

# At this point, I have the entire file in @data.
my @array;
foreach my $line (@data)
{
    push @array, [ split / /, $line ];
}

# There are a number of ways I could've written the above statement.
# Two others could be:
#
# my @array;
# push @array, [ split / /, $_ ] for @data;
# or
# my @array = map { split / /, $_ } @data;
#
# It's completely up to you what you're most comfortable with.

# At this point, we're ready to loop through the file. I'm 
# going to assume you want to print the second and fourth 
# elements of each line out. (That corresponds to array \
# indices 1 and 3.)
foreach my $line_from_file (@array)
{
    foreach my $value (@{$line_from_file})
    {
        # NOTE: Since I'm using array references, I have to
        # dereference the value using the -> (arrow) operator.
        print "2nd: $value->[1] ... 4th: $value->[3]\n";
    }
}