～んな is an another expression of ～るな. (る changes to ん） Basically, a verb+な makes a negative imperative expression. Thus, the verb do (する） + な makes 「don't do」. For example, - Don't do such things -> そんな事(such things)するな(don't do) - Don't eat this food yet -> この食べ物（this food)は、まだ(yet)食べるな(don't eat). - Don't take photos -> しゃしん(photos)をとるな(don't take) ～んな is an alternative word of るな; 　however, ～んな is a strong and rude form of るな. People may be impressed you as an aggressive person if you say 「～んな」 to someone. For example, - しゃべんな （しゃべるな）-> don't talk - すんな (するな） -> don't do - たべんな （たべるな） ->don't eat PS: You can use this construction for any verb that ends with る.

Dictionary form+な E.g たべるな、はなすな