IPA: /ˈpleɪnli/
KK: /ˈpleɪnli/
In a simple and clear way, without any confusion or complexity.
She explained the rules plainly so everyone could understand.
Plainly → It is formed from "plain" (from Old French *plain*, meaning clear or flat) and "-ly" (meaning in a manner of). The word "plainly" means in a clear or straightforward manner.
Think of something that is 'clear' ('plain') and done 'in a manner' ('-ly'). This helps you remember that 'plainly' means to express something clearly.