Bom Dia,
The FMGC calculates a VAPP speed depending on weight and the surface wind which you enter in the PERF APP page. (it is VLS+5 with light winds)
If in managed speed the autothrust will command this speed on approach.(read about GS mini to see how it changes with wind)
The pilot can overwrite VAPP if required by gusty conditions (up to VLS+15 per FCOM) or in the case of abnormal situation, the QRH gives an increment to add, there is a page in the QRH describing VAPP calculation.