I have a list (Teamsites) in SP 2013 onPrem with a people picker field (Owner).
Now I want show a counter of all list entries where the current user is standing in the Owner-Field.
using below REST API you will be able to get the filtered List Item
https://[Your SharePoint URL]/_api/web/lists/YourList/items?$select=Title&$expand=FieldValuesAsText/Owner&$filter=Owner eq 1
here in code
Owner eq 1 "1" is the current user ID which you can get using
Once you get the result from rest ,get the count in Success method using below code