To make something or someone look pretty, more beautiful or attractive.
Like putting make-up on and dressing up.
Or when you customize something to make it look pretty.
Or cleaning something up.
It's the act of making something look better.
Bob " What took you so long? "
Alice " I'm sorry, I needed to prettify myself some more."
"I prettified my room, I was tired of the old look"
To make something better looking or more attractive in a short amount of time for a small or moderate return on investment.
"I had to prettify my bosses reports so he didn't look like a complete looser at the meeting"
"I had to prettify my Xbox before listing it on Ebay"
"My girlfriend is coming over, hurry up and prettify the apartment"
To make oneself pretty
I wish to prettify myself with pretty clothes