Understand pg_stat_statements counters—without sharing SQL text

WITH analyzer_metadata AS (
  SELECT
    'databasemeter-pgss-v1'::text AS schema_version,
    current_database()::text AS database_name,
    current_setting('server_version')::text AS postgres_version,
    clock_timestamp() AS generated_at,
    NULL::timestamp with time zone AS stats_reset
)
SELECT
  m.schema_version,
  m.database_name,
  m.postgres_version,
  m.generated_at,
  m.stats_reset,
  s.queryid::text AS queryid,
  s.calls::double precision AS calls,
  s.total_plan_time::double precision AS total_plan_time,
  s.total_exec_time::double precision AS total_exec_time,
  s.mean_plan_time::double precision AS mean_plan_time,
  s.mean_exec_time::double precision AS mean_exec_time,
  s.rows::double precision AS rows,
  s.shared_blks_hit::double precision AS shared_blks_hit,
  s.shared_blks_read::double precision AS shared_blks_read,
  s.shared_blks_dirtied::double precision AS shared_blks_dirtied,
  s.shared_blks_written::double precision AS shared_blks_written,
  s.temp_blks_read::double precision AS temp_blks_read,
  s.temp_blks_written::double precision AS temp_blks_written,
  s.wal_records::double precision AS wal_records,
  s.wal_bytes::double precision AS wal_bytes
FROM pg_stat_statements AS s
CROSS JOIN analyzer_metadata AS m
WHERE s.dbid = (SELECT oid FROM pg_catalog.pg_database WHERE datname = current_database())
  AND s.queryid IS NOT NULL
ORDER BY s.total_exec_time DESC
LIMIT 500;