How to change the currency symbol according to language in site?
Have a look at the Currency module, here is a quote about it (from its project page):


  ... provides your website with currency conversion, currency information &amp; metadata, and amount/price display functionality.


This module facilitates Localized price display. Here is an excerpt from that link also:


  ... displays prices/amounts based on users' locales, so they are formatted in a way that is familiar to them. The different formats can be configured at Home » Administration » Configuration » Regional and language » Currency localization. Locales consist of a language and a country, and formatting patterns are configured per locale.