Please could someone explain to me, Is Google counting the word in the same plural of this word or not?
Google provides different results for the singular and plural versions of a keyword. So you have to include both versions in your page. Also you need to build backlinks with both forms of the word in the anchor text.
i was mark some time google count that. but in some case google can't count this thing. actually I don't know in which case google count or not? i will try so find this question also. if i will success then i will give you link or proper answer.
You should definitely use the singular AND plural forms of whatever keyword you're using. Computers, even search engines, can be dumber than you think!
I will usually optimize the meta tags, headings, etc for which every form of the word has a higher search volume, but you must optimize your content, internal links, and inbound links for both forms of the word. Obviously if one has a drastically higher search volume, then spend more time/effort on that one, but still optimize for both.