Employees
Employee records that payroll-related vouchers and payment methods link to - name, personal ID, address, IBAN, salary basis (monthly or hourly) and rate, and withholding tax percentage.
What it feeds
A salary-type voucher (Journal) can tag its lines with the employee it's paying, using that employee's own salary basis/rate as a starting point rather than typing the number in from scratch every pay period. See Settings → Payroll for the company-wide payroll defaults these vouchers also draw on.
Active vs. inactive
An employee who's left can be marked inactive rather than deleted, keeping their historical vouchers intact and out of active pickers.