Hi
Under watchOS 4.x, the Friends feature (which was available under some prior versions) is no longer included and there is neither a direct replacement for it nor a separate Contacts app on your Apple Watch.
When placing calls, sending new messages or sending emails, contacts can instead be selected:
From within the Phone, Messages and Mail apps:
- Calls: Make phone calls
- Messages: Send messages
Or, for calls and messages, by using Siri: