I heard that yahoo is now including Bing results, it’s true? …. might someone explain me in detail about this news
Yes it is true. Yahoo search results are powered by Bing. This is a joint share of both companies
If you do a Yahoo search, there is no indication that results have been included from anywhere else. Given that all the major search engines produce broadly similar search results for any given query, I don't know what your source believes is happening here.
This was a large influx of buzz around Yahoo Search results in few forums but I've not seen any official statements by either of them.