Hello Sophie,

I think that PolyLang support is the best place to ask that question, as we provide support for our themes only.

PolyLang documentation might be also helpful, take a look at this article:
https://polylang.pro/doc/strings-translation/

If you were using WPML to translate your site, here is a short tutorial how to get it to work with Integral Pro:
http://support.themely.com/forums/topic/how-to-translate-about-section-content-in-integral-theme/page/3/#post-1215

Let me know if you have any questions,
Piotrek