Here are some English terms that might describe a "sarguelas", depending on the specific details and context:
* Long skirt: This is the most basic description.
* Flowing dress: If it has a fitted bodice and a long, flowing skirt.
* Kaftan: A long, loose-fitting tunic with wide sleeves, often made of lightweight fabric.
* Maxi dress: A long dress that extends to the ankles or longer.
* Wrap dress: A dress that wraps around the body and ties at the waist.
* Gown: A formal, usually long dress.
Without further information about the specific garment you are referring to, it's difficult to give a more precise translation.