Terminology is simply language designed for a particular purpose. Over the years, music has acquired a vast amount of specialised terms. You don't need to learn them all like our poor singer here, but knowing a handful of the basics makes it easier for your director to, well, direct, and for you to understand what's expected. So here are the basics. You'll note that Italian is the language of music!
Volume:
Style:
Tempo:

(to get a feel for this, find a metronome or download a metronome app; here's one. The settings are usually marked.)