What do the percentages next to "1st Period" and "2nd Period" refer to?

The % refers to how each half day ("1st Period" / "2nd Period") is treated when an absence or remote working is taken. For example,  if "1st Period" is set as 50% and "2nd Period"as 20%, when the employee takes an absence on that day it will count as 0.70 days. If the employee only takes "2nd Period" as an absence, it will count as 0.20 days. The weightings can be used by HR to indicate whether an absence on a particular day (or half day) should be calculated differently to the expected normal workday for this employee. For example, if an employee has a 40 hour working week but is scheduled to work 10 hours every Monday, HR could change the weighting so that Monday counts as 1.25 days of work (or absence if an absence is taken on the Monday). Conversely, if the same employee is scheduled to work 6 hours every Friday, HR could change the weighting so that Friday counts as 0.75 days of work (or absence if an absence is taken on the Friday).