玩儿 is commonly used in Northern China, especially in Beijing and surrounding areas. The addition of “儿” (er) is a characteristic of the Beijing dialect, which often adds an “er” sound to the end of words, a phenomenon known as “erhua” (儿化)
玩 is more commonly used in Southern China and other regions where the “erhua” sound is not prevalent. It is the standard form without the regional dialect influence.
(verb) play; have fun; amuse oneself
(verb) trifle with; treat lightly
(noun) child
(noun) youngster
(noun) son
(adj) male