What does "Lisa, this is Alex, a friend of Patrick’s." mean in English for Spanish?

In English for Spanish, "Lisa, this is Alex, a friend of Patrick’s." means:

Lisa, este es Alex, un amigo de Patrick.

Listen to "Lisa, this is Alex, a friend of Patrick’s.": (If you have an HTML5 enabled browser, you can listen to the native audio below)

This is a phrase that is used in the GamesForLanguage English for Spanish Language Game in the following scenes:

• English for Spanish 4, Level 1, Scene 5