When combined, 搞不懂 (gǎo bù dǒng) literally means “to try to figure out, (but) not understand.” The character 搞 (gǎo) is the key ingredient, adding a layer of effort and personal involvement that the simpler 不懂 (bù dǒng) lacks. It transforms a passive state of not knowing into an active, and often frustrating, state of not being able to comprehend.