Any idea of how I can pass the value of my counting people application to Xprotect?

Please read this KB article, it might be helpful to give you an inspiration.

https://developer.milestonesys.com/s/article/DATA-FROM-ANALYTICS-HOW-TO-BEST-IMPLEMENT-A-SOLUTION

Thanks, I’ve already read it, I already find the documnetation about the Metadata stream, but you know if Xprotect support this integration?, like, if it support people counting?

Yes, there are many similar applications have been made by Milestone Partners, please see this - https://www.milestonesys.com/community/marketplace/start-exploring/?page=results&q=people%20count

So, you will be able to develop a solution so that you can submit data to XProtect and make it visible to operators in the Smart Client.

Out of the box XProtect does not support people counting but you can develop an integration to support it.