Go to Reports > Employees.
Look for the column 'Birth day' to find when employees celebrate their birthday.
You can sort this column on youngest -> oldest employee or the other way around.
If you want to do more with this data, you can download this report to Excel. This way you can sort them in any way you'd like.
Alternatively you can see birthdays in the Soigné app on the home page in the social feed.
Soon to be disabled: for now you can still use the old calendar feature to see birthdays as well. When you are in My Tasks, change your URL from https://portal.soigne.app/[my_account]/tasks to https://portal.soigne.app/[my_account]/calendar/list.
So put /calendar/list behind it.