This check determines whether the SharePoint farm and all SharePoint servers in the farm are up to date.
Microsoft releases monthly SharePoint updates to ensure that the bugs found in the product are fixed. In addition, new functionalities may be introduced with updates. Therefore, it is important to patch SharePoint regularly.
Please install Service Packs as soon as they are released. Cumulative Updates are not as thoughtfully tested as Service Packs and, although they introduce bug fixes and new functionalities, they can also introduce new bugs. Install Cumulative Updates only if they fix the problem you are facing.
Check SharePoint Updates Center for latest updates. To verify which build your SharePoint farm is running on, go to Central Administration > Upgrade and Migration > Check product and patch installation status.
Additional information can be found in the following articles: