It's a unix/linux crontab, for repetitive task. See https://en.wikipedia.org/wiki/Cron

It's minute, hour, day of month, month, day of week

In this case, repeat every 19th of july at midnight.

The file is a "cron schedule" [1]. Paste the series of numbers (and the *) into the box on the site below and you'll see it means "midnight on July 19th every year". The commenter will probably have this in their personal "crontab" file. They're emailing themselves every year on that date.

[1] https://crontab.guru/

Have a look at https://en.wikipedia.org/wiki/Cron#Overview.

In short: At 00:00 hours on 19/07 (i.e. July 19) execute that command. The * means 'regardless of what day of the week it is'.

This is a CRON Job and the notation indicates the time and frequency that an action should take place. https://en.wikipedia.org/wiki/Cron

it's a crontab file.

'0 0 19 7 ' means 'midnight of July 19th, regardless () the weekday.

It is example 2 from 'man crontab'.

It is crontab.