The kilo tt is a great first bike, its durable, and the parts are fairly good. Its a great feeling to constantly mod a bike, but, it's a waste of money to upgrade it all when the parts are all brand new. I'd run them down till the parts need replacing.

But if you wanted to know what parts the person probably changed I'll list them here

1inch threadless fork to 1inch threaded, since you need a threaded fork to use a quill stem
Those rims look like deep v styles with machined side walls for brakes
most likely a different crank (the arms connected to the pedals) and a new chain ring
pedals look the same, just different toe clip/straps
it looks like he also has a spoke count <36 (36 being the stock spoke count)
and colored tires!

I do recommend that rather than what it looks like in the picture where the person just put some oury style grips on the drops, you should properly use grip tape and tape it up, it looks 100000000x better in my opinion.

And dont worry about catching up on the words and terms, you'll learn what they are in time. Though if you want to learn it faster, go to a bike part site (retro-gression or benscycle) and click on the categories and in a while you'll know parts and terms.

Congrats on getting a bike, and I hope you love the kilo