WIll someone help me, what is happening in this command output?

root@Praveen:~# sudo systemctl status odoo12
● odoo12.service - Odoo12
   Loaded: loaded (/etc/systemd/system/odoo12.service; enabled; vendor preset: enabled)
   Active: active (running) since Sun 2019-02-17 12:07:33 +0545; 38s ago
 Main PID: 6731 (python3)
    Tasks: 4 (limit: 3502)
   CGroup: /system.slice/odoo12.service
           └─6731 /opt/odoo12/odoo-venv/bin/python3 /opt/odoo12/odoo/odoo-bin -c /etc/odoo12.conf

Feb 17 12:08:05 Praveen odoo12[6731]:     self._cnx = pool.borrow(dsn)
Feb 17 12:08:05 Praveen odoo12[6731]:   File "/opt/odoo12/odoo/odoo/sql_db.py", line 540, in _locked
Feb 17 12:08:05 Praveen odoo12[6731]:     return fun(self, *args, **kwargs)
Feb 17 12:08:05 Praveen odoo12[6731]:   File "/opt/odoo12/odoo/odoo/sql_db.py", line 608, in borrow
Feb 17 12:08:05 Praveen odoo12[6731]:     **connection_info)
Feb 17 12:08:05 Praveen odoo12[6731]:   File "/opt/odoo12/odoo-venv/lib/python3.6/site-packages/psycopg2/__init__.py", line 130, in con
Feb 17 12:08:05 Praveen odoo12[6731]:     conn = _connect(dsn, connection_factory=connection_factory, **kwasync)
Feb 17 12:08:05 Praveen odoo12[6731]: psycopg2.OperationalError: could not connect to server: No such file or directory
Feb 17 12:08:05 Praveen odoo12[6731]:         Is the server running locally and accepting
Feb 17 12:08:05 Praveen odoo12[6731]:         connections on Unix domain socket "/var/run/postgresql/.s.PGSQL.5432"? - - -
li

It is giving 500 internal server error.