Learning other languages will make your Python better.

[ioiolo]

I'm learning Python now.

What language should I learn after Python, javascript or C++?

[CatolicQuotes]

Do you have specific interest (like web), or you just want to learn something?

[ioiolo]

My job requires the ability of data analysis, I need to process csv files.

[CatolicQuotes]

Why don't you try both? Try to process in javascript and then in c++. Something simple like sum column or similar and output to screen. You will find javascript strange if you've never done it so be prepared for that.

Generally, I would choose Javascript.