I went to SharePoint 2013 central administration - Backup and restore - Granular Backup - Export a site or list and Exported a list which as .cmp extension.
Now how do I restore this list in different site collection?
Granular restore operations require the use of Powershell as no UI in Central Administrator exists.
This cmdlet is used to restore sites, list, and libraries exported with “export site or list” option in central administrator or using export-spweb cmdlet.
import-spweb -identity http://contosoweb/ -path \\appserver\bu\list.cmp
Note: You can’t decipher if a list or library is being imported into the contosoweb site using import-spweb. This has been predefined in the backup prior to running import-spweb.
What you should know about using import-spweb
Sites and subsites: Importing a site/subsite works as long as you specify a URL with a site that contains a matching template. For Example, importing a team site to http://contosoweb requires that I first provision a site using the team site template using URL http://contosoweb. Attempting to import to a site using a blank template or different template will result in an error.
List and Libraries: It’s important to determine exactly what items you want to import into a list or document library. If no items exist, then running the command in the example above will suffice and all items will be imported. What if a user accidently deletes 5 items out of 1,000 and you simply want to restore those 5 items? By default, the import-spweb cmdlet overwrites items if they exist with the restored version. In this case, the item version prior to restore can be salvaged by restoring the previous version as long as versioning is enabled. To prevent a scenario where you want items which currently exists to be ignored by import operation, you must include the -updateversions parameter with ignore
So in this example, to restore 5 items without affecting the 995 items which currently reside in a list named odst I can run the following:
Import-spweb –identity http://contosoweb/ -path \\appserver\bu\odst.cmp -updateversion ignore
Note: New Items created within the ODST library after initial export will not be touched by an import operation.