Shaswata Das

Don't by trendy, try to learn the basics and learn for future. For beginner Go is a great start, they're having a great documentation. Once you get Go, backend development wouldn't be a problem. I'll suggest you not to use and framework or library at the beginning. Do things from scratch, it may sounds inefficient, but hey! you'll learn more than others. Afterwards you'll be also able to do application development in Go.

For online banking, it'll be less computation intensive and more data intensive. So, Rails will be better than Python. I'll not recommend Node.js as it's not as scalable as those. If I had to choose indepently I would took Go.