Explain the following

debug1: Authentications that can continue: publickey
debug1: Next authentication method: publickey
debug1: Trying private key: /opt/atlassian/pipelines/agent/ssh/id_rsa
debug1: key_parse_private2: missing begin marker
debug1: read PEM private key done: type RSA
debug1: Authentications that can continue: publickey
debug1: No more authentication methods to try.
Permission denied (publickey). Please answer in JSON format.
user