Frontend and backend languajes

I'm currently planificating a web development for statistical analysis of big data of social media. I'm looking for some advice for good frontend and backend languages.

For backend i'm pretty sure i'll use Django, because python has a great capability for big data analysis but i'm lost in frontend languages.

I've seen some people that recommend going with JS, some people just stick to Django. Can you please give me some advice on this frontend languages, in which case should i use it and why?