An output jack is a small hole in a device where you can plug in a cable to send audio or video signals out of the device to another device, like speakers or headphones. Full definition
It also has an audio output jack which allows you to connect it to speakers or an audio system, allowing you to stream digital music from your PC to your audio receiver. (techradar.com)
You're not going to have a lot of fun streaming tunes directly on the device, but you can hook it up to external speaker via the 3.5 mm output jack. (androidcentral.com)
Both devices are now built with a 3.5 mm output jack, so you can connect them to an external speaker using an audio cable that will boost the sound quality. (digitaltrends.com)