I need to know clearly which languages are supported by Galileo Gen 2. For example , is Assembly Langusage supported or are other languages ? If someone can explain this, I'll be very glad. Thanks.
In default operating system for this board which is Yocto Linux you have support for C, C++, Python, and Node.js/Javascript programming. Please take a look under this link http://www.intel.pl/content/www/pl/pl/do-it-yourself/galileo-maker-quark-board.html
Of course you can also program this board with x86 assembly.
Keep in mind that you can use almost any language you want. You have to just port framework with bigger or smaller effort. For example if you want to use Go language you have to compile it by your own.. Here is an example how to do that on Raspberry Pi which will be quire similar for Intel Galileo. http://dave.cheney.net/2012/09/25/installing-go-on-the-raspberry-pi
In VxWorks operating system which is Real Time OS by default you have support only for C/C++.