This is the 13814th most frequent Spanish word.
sencillas
Simple.
The word "sencillas" describes the rooms as modest or basic in style or features.
Las habitaciones de ese hostal son muy sencillas.
The rooms in that hostel are very simple.
Here, "sencillas" characterizes the recipes as easy or uncomplicated to prepare.
Prefiero recetas sencillas para cocinar en casa.
I prefer simple recipes for cooking at home.
In this sentence, "sencilla" (singular form) implies understated or modest styling in clothing choice.