How to show current utilization of sessions, processes and other important settings for a database

Example:

set lines 300
col RESOURCE_NAME format a30
select RESOURCE_NAME,CURRENT_UTILIZATION,MAX_UTILIZATION,INITIAL_ALLOCATION,LIMIT_VALUE
from v$resource_limit
where resource_name in ('processes','sessions');

RESOURCE_NAME                  CURRENT_UTILIZATION MAX_UTILIZATION INITIAL_ALLOCATION     LIMIT_VALUE
------------------------------ ------------------- --------------- ---------------------- ---------------
processes                                     1498            1500       1500             1500
sessions                                      1511            1517       2272             2272

Documented for Oracle 19c here