Not all jobs are easy "9 to 5" jobs on a single day. Sometimes you may have a crew working from one day into the next. A job can be denoted as a 'Night Shift', which will allow any employees clocked-in to it to have time entries stretching into the next day.
A job can be set as a night shift when creating/editing it, and once that has been done, it will have a little 'moon' icon indicating the change.
Please note: You may need to enable the 'night shift' setting in your miscellaneous app settings to use this feature. You can read more about FieldClock's app settings, as well as how to access and change them, here.
Once your job is set as a night shift, any time entries of employees there will automatically be allowed to stretch past midnight and into the next day. If this has happened, you will see little date in the mm/dd format (the date of the next day that they stretched into) below their time entry.
Do also note that an employee will never be able to stretch in to two days, as their time entry's length will still be capped to 24:00.