Don't read 省 as shěng here — it's xǐng. The character 省 has two readings: shěng (province; to save) and xǐng (to examine; to become aware). 反省 uses the xǐng reading.
culture
Confucius's student Zengzi famously said 吾日三省吾身 (wú rì sān xǐng wú shēn, 'I examine myself three times daily'). This phrase from the Analerta is still widely quoted in Chinese education.