IPA: /ˈʃaɪnɪli/
KK: /ˈʃaɪnɪli/
In a way that reflects light; brightly or with a smooth surface.
The car gleamed shinily under the sun.
Shinily is formed from "shine" (from Old English "scīnan", meaning to emit light) and "-ly" (a suffix meaning in a manner of). The word "shinily" means in a manner that emits light or reflects brightness.
Think of something that 'emits light' ('shine') and how it does so 'in a manner' ('-ly'). This helps you remember that 'shinily' describes how something shines.