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

Results forbeanstalk-playground.happycode.nl

Logged At	Not Before	Not After	Common Name	Matching Identities	Issuer Name
2020-10-30T23:35:10.293	2020-10-30T22:35:09	2021-01-28T22:35:09	beanstalk-playground.happycode.nl	beanstalk-playground.happycode.nl	C=US, O=Let's Encrypt, CN=Let's Encrypt Authority X3
2020-10-30T23:35:10.045	2020-10-30T22:35:09	2021-01-28T22:35:09	beanstalk-playground.happycode.nl	beanstalk-playground.happycode.nl	C=US, O=Let's Encrypt, CN=Let's Encrypt Authority X3
2020-10-30T23:19:56.077	2020-10-30T22:19:55	2021-01-28T22:19:55	beanstalk-playground.happycode.nl	beanstalk-playground.happycode.nl	C=US, O=Let's Encrypt, CN=Let's Encrypt Authority X3
2020-10-30T23:19:55.91	2020-10-30T22:19:55	2021-01-28T22:19:55	beanstalk-playground.happycode.nl	beanstalk-playground.happycode.nl	C=US, O=Let's Encrypt, CN=Let's Encrypt Authority X3