@cities is a list. $cities[0] is the first. foreach walks.

Goal

Say cities and a pushed Eldoret.

use strict;
use warnings;
use feature 'say';

my @cities = ("Nairobi", "Mombasa", "Kisumu");
say $cities[0];
say scalar @cities;

use strict;
use warnings;
use feature 'say';

my @cities = ("Nairobi", "Mombasa");
push @cities, "Kisumu";
say join(", ", @cities);

use strict;
use warnings;
use feature 'say';

my @cities = ("Nairobi", "Mombasa", "Kisumu", "Nakuru");
say join(", ", @cities[0, 1]);

use strict;
use warnings;
use feature 'say';

my @units = (12, 8, 5);
say join(", ", @units);