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

Results for*.staging.angularconsole.com

Logged At	Not Before	Not After	Common Name	Matching Identities	Issuer Name
2018-09-29T15:12:23.836	2018-09-29T14:12:23	2018-12-28T14:12:23	*.staging.angularconsole.com	*.staging.angularconsole.com	C=US, O=Let's Encrypt, CN=Let's Encrypt Authority X3
2018-09-29T15:12:23.836	2018-09-29T14:12:23	2018-12-28T14:12:23	*.staging.angularconsole.com	*.staging.angularconsole.com	C=US, O=Let's Encrypt, CN=Let's Encrypt Authority X3
2018-09-29T15:12:23.268	2018-09-29T14:12:23	2018-12-28T14:12:23	*.staging.angularconsole.com	*.staging.angularconsole.com	C=US, O=Let's Encrypt, CN=Let's Encrypt Authority X3
2018-09-29T15:12:23.268	2018-09-29T14:12:23	2018-12-28T14:12:23	*.staging.angularconsole.com	*.staging.angularconsole.com	C=US, O=Let's Encrypt, CN=Let's Encrypt Authority X3