HI!

Follow the instructions: 

1. Take file languages/thegem.pot or xx_YY.po from theme directory .

2. Open file with Poedit software.

3. Translate necessary strings to your language.

4. In software open Catalog - Settings and set Language to Translation to xx_YY.

5. Then save file as thegem-xx_YY. You must have two files thegem-xx_YY.po and thegem-xx_YY.mo.

6. These files you need to put to the wp-content/languages/themes of your site.

With same operation you can translate TheGem elements plugin.

Just put  translations in wp-content/languages/plugins

or you need to edit:

wp-content//themes/thegem/woocommerce/cart/cross-sells.php

wp-content//themes/thegem/woocommerce/single-product/related.php