I am in manual testing from last 5+ years and having a sound experience in it. Now I want to switch in automation testing and want to start with Selenium.
I don't have any programming experience or knowledge in either Java and C#.
Robotframework-seleniumLibrary is a good choice, if you want to get involved with less coding and more test automation.
Python or Java may be a good choice to start with, if you want to focus on test automation.
Python is widely considered best language for beginners, much simpler than Java or C#.
Once you understand programming in Python, it will be easier to learn other languages (and you will understand why Python is easier).
But before all this, you should learn how to use Google. This exact question is asked on this exact forum every week.
Everything has a context.
Will you join or start an automation project? Follow the language of this project.
Do you want a fast learning curve on the basics of programming and automation? Take a look in Python; do a Codeacademy-like course and play with each entry on the Learn X in Y Minutes site - try run and change things to see what happens. After that, learn the Page Object pattern auto-critically, always checking if you are building something extendable, using good OO programming. The Python tutorials and courses lack sometimes this sort of critic.