IPA: /ˌʌn.kəm.prɪˈhɛn.dɪŋ/
KK: /ʌnˌkɑːmprɪˈhɛndɪŋ/
Not able to understand something; lacking knowledge or awareness about a subject.
She looked at him with an uncomprehending expression when he explained the complex topic.
Uncomprehending → It is formed from "un-" (meaning not) and "comprehendere" (meaning to grasp or understand). The word describes a state of not being able to grasp or understand something.
Think of 'not' ('un-') being able to 'grasp' ('comprehendere') something — that's why uncomprehending means not understanding.