Data Science Is a vast legacy technology where you should have the knowledge of many other skills like Mathematics , statistical, probability, programming languages like python java etc. I suggest you to build all the necessary basic and the go for a Data Science with Python course when you think you have good basic .
Yes there are many online content where you can get to know what exactly Data Science is and how it works. It is very important to have good knowledge about its application and usage as it will help you in understanding the concept very well.
Some of the good online Sources where you can get good information about Data Science in the form of Blog or Article are Edureka, Reddit, Quora.