"扣除物价因素" can be translated into English as "after adjusting for price factors" or "excluding the impact of price changes".
For example:
The real growth rate is calculated after adjusting for price factors. （扣除物价因素后计算的实际增长率。）
The figure reflects the increase in quantity, excluding the impact of price changes. （该数字反映了数量的增长，扣除物价因素。）