IPA: /ʌnˈsɜːrtənli/
KK: /ʌnˈsɜrtnli/
In a way that shows doubt or lack of confidence.
She spoke uncertainly about her plans for the future.
Uncertainly → It is formed from "un-" (meaning not) and "certain" (from Latin "certus", meaning sure or fixed) and the suffix "-ly" (meaning in a manner). The word "uncertainly" means in a manner that is not sure or fixed.
Think of 'not' ('un-') being added to 'sure' ('certain') to remember that 'uncertainly' describes something done in a way that lacks certainty.