Now you know what it is, but you need to know that day trading is not easy for most of the people. I advise you first to get into the usual trading or long term trading as we call it, just to feel the whole thing. After you get some experience you could do this one too if you like it.
Yes, this point is very important for a newbie. Because day trading is almost like a gambling just a guessing game and in this guessing game many times we will do a mistake and even experts can't predict things every time correct. So if your a new to trading then first start with investing and slowly learn how this trading works then can try your luck in day trading.
Day trading like every other form of trading is no guess work or gaming, but can actually end up being one if that's what the trader wants it to be. Trading of any type is risky, knowledge and skills are highly necessary less it becomes an instance why people say, trading is gambling.
For the meaning of day trading, it simply means a trader usually do not carry over his open positions to the following day, but closes them within 24 hours and in most cases with little profits, but since it can be done several times a day and done properly, the profits can add up.