Yes! Just follow these steps and your store will be multi-lingual in no time!

Step 1) From your Dashboard click on the Account link in the top right hand corner.
Step 2) On your account page, click the "Create a new store" button in the top right hand corner.
Step 3) Create a new store in the second language you would like your store to be in. To change the language of a store, simply go to System -> Settings -> Local and select the language you would like to use. This will be a totally new store, so you can customize which products you'd like to sell, product descriptions, the default currency, etc.
Step 4) Next to where you can select the language (Stystem -> Settings -> Local) you will see a "Use Multi-Lingual" link. Click on that, and then click the "Use Multi-Lingual" button at the bottom of the window that pops up. Make sure to save these settings!
Step 5) There will now be a language option on your store front next to the currency option. When your customer chooses the language they'd like to use, they will be taken to the corresponding site.

Note: This feature is only available to Professional stores and above. If you are currently using a Basic or Advanced account, you will need to upgrade to access this feature. Here's a full list of the benefits of upgrading.