It can be anything! An apex, subdomain, or even a URL.

Results for*.staging.best4software.com

Logged At	Not Before	Not After	Common Name	Matching Identities	Issuer Name
2021-01-19T15:02:04.192	2021-01-19T14:02:03	2021-04-19T14:02:03	staging.best4software.com	*.staging.best4software.com	C=US, O=Let's Encrypt, CN=R3
2021-01-19T15:02:04.192	2021-01-19T14:02:03	2021-04-19T14:02:03	staging.best4software.com	*.staging.best4software.com	C=US, O=Let's Encrypt, CN=R3
2021-01-19T15:02:03.951	2021-01-19T14:02:03	2021-04-19T14:02:03	staging.best4software.com	*.staging.best4software.com	C=US, O=Let's Encrypt, CN=R3
2021-01-19T15:02:03.951	2021-01-19T14:02:03	2021-04-19T14:02:03	staging.best4software.com	*.staging.best4software.com	C=US, O=Let's Encrypt, CN=R3