This is the 5862nd most frequent Catalan word.
guillermina
"Guillermina" refers to a type of women's shoe, typically flat and with a strap across the instep, known as a "Mary Jane" in English.
Here, 'Guillermina' is a proper noun used as a first name.
La meva tieta es diu Guillermina.
My aunt's name is Guillermina.
'Guillermines' in this context refers to a type of footwear, specifically Mary Jane shoes.
Vaig comprar un parell de guillermines noves per anar al casament.
I bought a new pair of guillermines for the wedding.
In this sentence, 'guillermina' is used as a reference to the term itself, invoking nostalgic feelings.