The 2009 GMC Acadia may have Bluetooth, depending on what trim level you purchase and the features that the original owner added. On the SLT-1 and SLT-2 trims, Bluetooth is a standard feature, but on the SLE trim, it’s optional.
As a result, your Acadia may have Bluetooth, but if you’re going to buy the SLE trim, you should double-check to ensure it has it. Keep in mind that you can’t stream audio with the 2009 GMC Acadia Bluetooth system. It only works for hands-free calling and voice recognition. Music streaming through Bluetooth didn’t become widely available until around 2012 and 2013.