@Tomyxas
Oh I got you know, I though it is showing different character.
It seems Open Sans fonts does not have these letters, however I do not know better font family for this.
What I recommend is:
- remove Open Sans family from your site
- or set font-weight to 600 on titles and strings, that are problematic
- or set font-size lower or equal to 17px (this problem seems to be only with fonts larger than 18px)

Can you say where i could change font weight and size?

@Tomyxas
Everything is stored in file:
oc-content/themes/zara/css/style.css

Open your site using google chrome, right click on element (where you want to change it) and choose "Inspect".
It will show you which line is related to that block/element.

I.e. if you do it on "Browse Categories", you will see line is related to #top-cat h1,... find this line in style sheet and change font size to 17px and save.

I fixed it. I deleted your font files from font folder. Then I edited header.php file and changed line osc_enqueue_style('open-sans', '//fonts.googleapis.com/css?family=Open+Sans:300,600&subset=latin,latin-ext'); to osc_enqueue_style('open-sans', 'https://fonts.googleapis.com/css?family=Open+Sans:400,600,700,800&subset=latin,latin-ext');

Now letters looks good.

Thank you for your support.

@Tomyxas
Cool, welcome.