By the word itself day trades, obviously you earn by trading daily or short term even if you get a little amount by it, you can still earn a decent amount if you stake a huge amount of money to buy coins and used it for day trading but it is also the riskiest thing you might do. Day trading became possible due to the high volatility of cryptocurrencies.
Exactly, to make it simple to understand regarding on trading process it is a way to sell and buy of your own shares of crypto currency as you will exchange it to suitable crypto currency would you like for. Basically, most of is bitcoin since bitcoin is the dominant crypto currency here in the cyberworld but somehow there are some exchange sites in which not just bitcoin but other crypto currency having a potential to increase.