Here's a search on Google for my site.Texts are different for each page of my site but snippets (meta description) are still the same for a Google search.Can you give me an advice to change it?
Google shows duplicate meta description in its index
google index;meta description
All your pages have same meta description like below.  <meta http-equiv=content-type content=text/html; charset=utf-8 />  <meta name=keywords content=  -   ,  ,  , ,  ,   ,    ,  ,  , it ,  ,   />  <meta name=description content=  -   ,  ,  , ,  ,   ,    ,  ,  , it ,  ,   />  <meta name=generator content=Joomla! - Open Source Content Management />From your source code, I just figure out all the pages have same meta description.You're using Joomla. So in admin section global meta keywords and description takes if you are not set any description or meta data to individual pages.So the solution is you have to set different meta data from you article section or menu sections in Joomla.