While you don’t give exact model of your Yamaha keyboard, it’s hard to tell … but probably USB only carries MIDI data and if you want to record Yamaha’s audio, you need to connect it’s analog outputs to your soundcard/audio interface.
As Strophoid already said, it works just like a hyper-fast hard drive.
To be honest … it’s quite small in today’s standards. It was OK 6 years ago (when I bought my first SSD) to hold Windows XP and your basic software, but with Win7 (or 8) and modern software packages it requires some planning (or even serious IT skills) to fit everything into 32G.
If you’re looking at primary monitors at this price range I would recommend Adams or KRKs instead of Yamaha.