Hi Hassan,
{%
cultureLocalizedName = GetResourceString(" " + CultureCode, (CultureCode == "de-de") ? "German" : ((CultureCode == "nl-nl") ? "Dutch" : "Englich"));
return;
%}
<li>
<a title="{% cultureLocalizedName %}" href="{%HTMLEncode(URL)%}">{% cultureName %}</a><img src="/Root/media/Folder/{%cultureName%}.png" />
</li>
use above code in transformation with XML transformation type and add your flag icon in media libraries using file name cultureName.png like Dutch.png. I have used it and it's working fine for me.
Thanks,