IPA: /ˈsɔːf.tli/
KK: /ˈsɔf(t)li/
In a gentle or quiet way; not harsh or loud.
She spoke softly so as not to wake the baby.
Softly → It is formed from "soft" (from Old English *softe*, meaning gentle or mild) and "-ly" (meaning in a manner of). The word "softly" means in a gentle or mild manner.
Think of being gentle or mild ('soft') and how the '-ly' makes it describe the way something is done. This helps you remember that 'softly' means to do something in a gentle manner.