Hello,

I need to translate some things in article detail, but I can't do it.
Next thing what I need hide socials in article bottom.

See the attachment please.

Thanks in advance.
Filip.

The social buttons are most probably a part of your template.

In order to translate K2 you have to install the appropriate language pack.
getk2.org/extend/translations

To change the date format you can override the language string.
docs.joomla.org/Language_Overrides_in_Joomla

This link will show you all the available date formatting options.
php.net/manual/en/function.date.php

Hello, thanks for reply, but I have already instaled language pack, but "Published" is still in English, same as "Category"
Thanks

Then it was probably not installed correct.
You can always override these language strings.

K2_PUBLISHED_IN
K2_CATEGORY

Also check your files to make sure that these language strings have not been altered.