Parse and understand cron expressions with human-readable descriptions.
A cron expression is a string of five fields separated by spaces that represents a schedule for recurring tasks. The fields represent minute (0-59), hour (0-23), day of month (1-31), month (1-12), and day of week (0-7). Special characters include * (any value), , (list separator), - (range), and / (step values). Cron is widely used in Unix/Linux systems, cloud functions, and job schedulers.