Painfully basic php syntax question

1

in a statement like:

<?php if ($block->subject): ?>...<?php endif; ?>

what does the “->” mean. this information seems strangely elusive from w3schools.

also in a statement like:

$families = array
(
  "Griffin"=>array
  (
  "Peter",
  "Lois",
  "Megan"
  ),
  "Quagmire"=>array
  (
  "Glenn"
  ),
  "Brown"=>array
  (
  "Cleveland",
  "Loretta",
  "Junior"
  )
);

what does the “=>” mean?

If there is a site or page at w3schools that lists this information PLEASE point me to it.