Ismael Luna Dominguez entered guilty pleas to one charge of grave and criminal assault and one charge of common assault in the Royal Court on Friday.
The assaults took place in July and August this year at a premises in St. Helier.
He also admitted an additional count of perverting the course of justice by attempting to telephone a woman, sending her a letter, and asking his parents to contact her.
Advocate James Bell represented Dominguez, who will be sentenced on 17 January 2020 at 10:00.
He has been remanded in custody in the meantime.