IPA: /ɪˈlɪtəˌrɛtli/
KK: /ɪˈlɪtəˌrɛtli/
In a way that shows a lack of education or ability to read and write.
He spoke illiterately, making it hard for others to understand him.
Illiterately → It is formed from "il-" (meaning not), "literatus" (from Latin, meaning educated or learned), and "-ly" (meaning in a manner). The word "illiterately" means in a manner that is not educated or lacking the ability to read and write.
Think of 'not' ('il-') being combined with 'educated' ('literatus') to remember that 'illiterately' describes someone who is not educated in reading and writing.