Since Travelify theme is not yet available in Bulgarian language you will have to translate it yourself. Here is a detailed tutorial on how to translate it: https://colorlib.com/wp/2013/how-to-translate-wordpress-theme/
If you will translate it completely you can send me your translation file and I will add it to the default theme installation. I will provide a link back to your website from as reward.
Excerpt length you can adjust by placing Excerpt manually when editing post. There should be a box called “Excerpt” underneath Post edit page. If you can see that you can enable it via “Screen Options” in the upper right corner.
If you want to automate this process you can use filter for Excerpt length. You can read more about it here: http://codex.wordpress.org/Function_Reference/the_excerpt.
Code related to Excerpts you can find inside content-extensions.php located in Theme folder – library – structure.