Because the authoritative number lives in a spreadsheet updated monthly, and the employee's own count is based on memory. Both are approximately right, which is the worst kind of right.
The running entitlement per person per leave type, accrued by the policy that applies to them and adjusted by what they have taken.
Accrual runs from the policy: rate, carry-over cap, and any pro-rating for joiners and leavers. The balance is visible to the person and shown to the approver at the point of decision.
Somebody requests five days. The approver sees they have six remaining, that two colleagues are already away, and approves or does not on that basis.
It does not interpret statutory minimums for you. Accrual rules and caps are configured per policy and per country by you.
Payroll reads balances where untaken leave is paid out. Year-end carry-over applies the cap automatically rather than by hand.
Carry-over applies your cap; anything above it lapses or is paid, per policy.
Only if you allow advance leave in the policy.
Yes, from the start date on the personnel record.
Fourteen days, every module, no card. Or half an hour with someone who will run it on your own records and tell you where it does not help.