Explanation

Box 1: 0 0 4 * * 1-5
Azure Functions uses the NCronTab library to interpret NCRONTAB expressions.
An NCRONTAB expression is similar to a CRON expression except that it includes an additional sixth field at the beginning to use for time precision in seconds:
{second} {minute} {hour} {day} {month} {day-of-week}
NCRONTAB time zones
The numbers in a CRON expression refer to a time and date, not a time span. For example, a 5 in the hour field refers to 5:00 AM, not every 5 hours.
The default time zone used with the CRON expressions is Coordinated Universal Time (UTC).
To have your CRON expression based on another time zone, create an app setting for your function app named WEBSITE_TIME_ZONE.
1-5 is weekdays
Box 2: 0 0 4 * * 1-5
Reference:
https://docs.microsoft.com/en-us/azure/azure-functions/functions-bindings-timer?