"You give that girl a slice of cake."
Translation:Tu îi dai acelei fete o felie de tort.
Our way of saying to this/that girl is acestei/acelei fete. Feminine things seem to transform this way into something looking like the plural. We know it is not the plural because acestei/acelei (fete) indicates the singular, while acestor/acelor (fete) would indicate plural.
I think it's called declination and it is based on case and article.
For masculine and neuter things, we seem to use a form that looks like the singular:
- acestui/acelui băiat (singular masculine), acestor/acelor băieți (plural masculine)
- acestui/acelui scaun (singular neuter), acestor/acelor scaune (plural neuter)
So the strange phenomenon seems to be happening for feminine things.