Interface services don't have very descriptive names by default in Check_MK. Out of the box, these services are named "Interface #" as they're discovered, with an integer in place of the #.
This is great from one perspective, and frustrating from a dozen others.
To alter this behavior, open your Rulesets in WATO
Seach for alias and open the ruleset Network Interface and Switch Port Discovery
Choose the appropriate folder and click Create Rule in Folder
Give your rule an appropriate name, and in the Value section, check the box beside Alias as service name for network interface checks. Ensure Use Alias is chosen below it.
Once you Save the new rule, you'll need to Commit the changes.
Don't forget to Bulk Discover your hosts!
The result? Great interface service names!