I am planning on writing an application that will run on both Android and IOS. I've read and watched some tutorials online but I'm still confused. I know my questions might be obvious but please help me.
You can go for ReactNative by Facebook if you want to make app for android and ios both. But it also depends on your requirement. ReactNative is best use for small apps. As ReactNative does not provide much flexibility while using third parties app and obviously for this you should be knowing JS.
For enterprise level apps you can use both Native and ReactNative together like myntra is doing.