So explain this to me like I am 5 years old. You saying folks buy the coin cheap on hotbit and sell of for a higher price on another exchange?
Arbitrage is essentially when you have a coin or stock and it is selling for $50 on one exchange, but it is selling for $58 on another exchange. People will buy for $50 on the exchange where it's price like that, and then move to the exchange where it's selling for $58, and sell it for $58. Assuming it was bought and sold for those exact amounts, you'll net $8/coin/stock you bought and sold.
It's easier said than done with some coins, as prices can even out pretty quickly across exchanges.