Buying on margin isnt only isolated to cryptocurrencies.
To learn about that, I suggest a site like investopedia.com and doing a search for margin buying there.
Basically, it is a way of leveraging your purchase by taking say, 1,000 but buying like you had $10K worth of money. If the asset goes up 10%, the total gain would be $1000 which would double your initial money (less the margin costs). Of course, if it goes down 10%, you would have a margin call meaning they close the trade and keep your $1,000.
I am not sure which brokers offer margin buying on tokens but I would suggest you avoid it. That is a technique for highly advanced traders.