This is the 720th most frequent Spanish word.
registro
"Registro" means "record," "register," or "registry" in English, depending on context.
Here, 'registro' refers to a list or record of participants or attendees that is kept or to be made.
El registro de asistentes al evento se cerrará mañana.
The registration of attendees for the event will close tomorrow.
'Registro' in this context indicates the action of documenting or recording information for a particular purpose.
El registro de los datos personales es obligatorio para acceder al sistema.
The recording of personal data is mandatory to access the system.
In this case, 'registro' means the particular range or scope, referring to the singer's ability in pitch or vocals.