IPA: /ˈprɪt.ɪ.li/
KK: /ˈprɪt̬.ɪ.li/
In a way that is attractive or pleasing to the eye.
The flowers were arranged prettily on the table.
Prettily → It is formed from "pretty" (from Middle English *prity*, meaning attractive or pleasing) and "-ly" (meaning in a manner of). The word "prettily" means in a manner that is attractive or pleasing.
Think of someone acting in a way that is 'pleasing' or 'attractive' — that's what 'prettily' means.