WOW! I bought 3800Sat right now

and price rised up 4600
i keep seeing you guys talk about buying SAT (satoshi) what the hell does that mean ;/ ? i tried looking up satoshi and how it converts to a calculation but i cant seem to find a clear answer on it.
they rather mean that they are buying or selling at xxxx satoshi, signatum and all altcoins are being traded in pair with BTC (1 BTC = 100,000,000 satoshis)