I don’t know the meaning of the Spanish term exactly, but if it means you’re in training we usually say Nurse trainee or Nurse in training. But that would only be if you needed to put a job title down for something. If you just wanted to tell someone what you do you would say I’m training to be a nurse. If it means you’re a practicing Nurse then you just say you’re a nurse. All of this is for American English. I can’t say if there’s a different for British English.

Yeah that works. You could also say "nurse in training"