What does "It’s about a 30-minute walk." mean in English for Spanish?

In English for Spanish, "It’s about a 30-minute walk." means:

Está a unos 30 minutos a pie.

Listen to "It’s about a 30-minute walk.": (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 3, Scene 3