Update api-concepts.md

content/en/docs/reference/using-api/api-concepts.md

@@ -365,7 +365,7 @@ data:
   key: some value
 ```
 
-The above object contains a manager in `metadata.managedFields`. The manager object consists of basic information about the managing entity itself, like operation type, api version, and the fields managed by it.
+The above object contains a single manager in `metadata.managedFields`. The manager consists of basic information about the managing entity itself, like operation type, api version, and the fields managed by it.
 
 Note that this field is managed by the apiserver and should not be changed by the user.