PSQL please also explain query thank you!

Write a query against the employees table. Return 3 columns Column 1: birth month (as an integer) Column 2: birth quarter (as an integer) Column 3: number of employees born in that month/quarter Expected Results: Your query should return the exact same data with the same exact labels. PART 2) There are 12 months in a year and 4 quarters in a year. Why does this query return 12 rows and not 48 rows? (124)