While trying to install moodle 3.6 on Windows i am getting error for extension
php extension intl
php.setting opcache.enable
while i made the relevant changes in php.ini file still facing same error.
You don't tell us what your operating system is, so it's hard to help.
The intl extension is required. Making a change in php.ini will only work if you are running Windows. On (say) Linux you would need to load the intl package (depending on how PHP was installed).
Opcache is optional and won't stop you installing.
Whatever happens, if you install anything or make changes in php.ini you will need to restart the web server.
Madhukar, I assume that you are trying to install the "Moodle installer package for Windows." If so, the last time that I tried to install this package I ran into the same problem. As Howard points out, the "opcache" is a warning and doesn't affect the installation progress. But it's that "intl" extension that is the problem. I don't understand why "intl" isn't installed in the Windows download, it is installed in the Mac download. Maybe someday this "intl" issue will be fixed in the Windows download (if it has not been already.) I am not skilled in all of these Linux setups, so I have never had success installing intl from scratch.
In the past, to install a local version of Moodle on the PC, I have had success installing XAMPP, then manually installing Moodle.
If you're using the Install Packages for Windows, hopefully you downloaded and installed the Microsoft Visual C++ 2015 Redistributable package as stated in the instructions.
Check that it is the 32-bit package that you installed (vc_redist.x86.exe) not the 64-bit package (vc_redist.x64.exe).