Zero-based lists. foreach walks. [] appends.

Goal

Echo cities and a pushed Eldoret.

<?php
$cities = ["Nairobi", "Mombasa", "Kisumu"];
echo $cities[0], PHP_EOL;
echo count($cities), PHP_EOL;

<?php
$cities = ["Nairobi", "Mombasa"];
$cities[] = "Kisumu";
echo implode(", ", $cities), PHP_EOL;

<?php
$cities = ["Nairobi", "Mombasa", "Kisumu", "Nakuru"];
echo in_array("Eldoret", $cities) ? "yes" : "no", PHP_EOL;

<?php
$units = [12, 8, 5];
echo implode(", ", $units), PHP_EOL;