A PHP class (or interface) maps to an UML Class (or Interface).
A PHP function maps to an UML Operation.
A PHP property, or class constant, maps to an UML Attribute.
Packages do not exist in PHP, like they do in Java. There are two possible ways to mimic them:
by using the docblock @package in the comment of a class (or of a file)
by interpreting the namespace of a class
In UML 1.4:
A PHP file maps to an UML Component.
A physical folder maps to an UML Subpackage.
In UML 2.1:
A PHP file maps to an UML Component.
A physical folder maps to a nesting UML Component.