I have created sharepoint sites in my Windows server 2012 R2.
Now I wanted to install windows server R2 in another Machine(Computer) and then move my sharepoint sites plus farm there.
Is that possible guys?
This is certainly possible, but it involves more than just copying some files around.
You'll need to migrate the farm from the old server to the new server. If you had a separate SQL Server, you could have installed SharePoint (to the same patch level) on the new server, joined this server to the farm, enabled the required services, then removed the old server from the farm to perform the migration. As the SQL Server is running on the same server however, this is a little more complicated.
There are a couple of routes to doing what you need to do:
The second option has two possible routes. The first is to use the SharePoint backup and restore functionality to migrate the settings to the new farm. Instructions for doing this can be found at https://technet.microsoft.com. Using this procedure, you create a new farm with a configuration database only, then create a settings-only backup from your production farm and restore this to the second farm. You will also need to copy the content databases form your production farm to the second farm and attach them to the content web applications. There are some simple instructions for this part at https://sharepointzee.wordpress.com (note these instructions are for SharePoint 2010, but the steps are the same).
You second method is to create another farm with the same settings - build a new farm (ideally using PowerShell) taking the service application and content databases from the source farm to the new farm a part of the build process. When creating a service application for example, if you specify the name of a database that already exists on the SQL Server used for the farm that is the correct type (and suitable version), this database will be used for the service application and therefore all settings and data that are included in the database will effectively be migrated to the new farm for the service application you've just created. Obviously your new farm will have to be either the same patch level or newer than the source farm. This latter method requires more knowledge of SharePoint, but is likely to generate you a more suitable farm for your organisation.