Google translator says that 勉強しなよ is "don't study" and deepl says that it is "study" ._.
DeepL is right. The なよ at the end in the picture is an informal, somewhat masculine command modification of the verb する. She's saying something like, "C'mon, study." 勉強するな would be the negative imperative, add よ to that in order to make it more informal.
