To add an absence per period for multiple employees and/or days, go to Operations - Team Manager. Select the employees you want to add absences in with CTRL/SHIFT and right-click - Absence operations - Absence by period. You can also select columns and rows.
Adding multiple-cell absences in Team Manager in Astrow Web from the options bar
Add absence window opens. It estimates the start and the end based on the cells selection or the period in Team Manager (in case of single cell selection), and you can add the absence for the employees selected.