-> is not the same thing as =>
-> is used with objects to "point" to a method of the object to call, or a property value. For example:
$myClass->email='admin@example.com';
This says assign the value admin@example.com to the email property of the $myClass object.
=> is used with arrays in PHP. One example:
$arr = array('fruit' => 'apple');
The => in this case is used to assign the value apple to the fruit "index" within the $arr array.
=> is also used in looping over arrays, in particular over "keyed" arrays. Keyed arrays or as they are also called, hashes, use strings to access the items in the array. The previous example uses fruit as a key in the $arr array. To loop over the array, one way to do it would be:
foreach ($arr as $key => $value) {
echo($key . ': ' . $value);
}
This loops over the array, and for each item, $key is set to the key name, in our array example the first item is fruit. $value is assigned the value stored in the array with the key name, in this case apple.
Please do read up more:
PHP operators
PHP Arrays
PHP Classes
Make sure to visit the links on the left hand side of each page and there is further discussion of the main topic.
The PHP.net site in general is quite useful in figuring out what is going on, so please do wander around it.