What does "I’m sure you’ll be able to find one in one of the shops." mean in English for Spanish?

In English for Spanish, "I’m sure you’ll be able to find one in one of the shops." means:

Estoy segura de que podrás encontrar una en una de las tiendas.

Listen to "I’m sure you’ll be able to find one in one of the shops.": (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 3, Level 2, Scene 11