The Salary pay item has been defined with a calculation type of 'Salary' which means that the annual salary effective at the pay date is divided by the number of pay periods per year entered in the Pay Group set up screen.
Note that this can be over-ridden using a factor entered in the Pay Item set up screen. If a factor is entered in the Pay Item set up screen for the Salary payment, the factor is divided into the annual salary amount in order to provide the pay period amount.
The Pay Item has been set up to repeat automatically each pay period so that the payment will be carried forward to the next pay period when it is opened.