This is the 209th most frequent Greek word.
εκείνη
"Εκείνη" means "that (feminine)" in English.
The word "εκείνη" is used here as a demonstrative pronoun to specify which woman is being referred to.
Εκείνη η γυναίκα είναι πολύ έξυπνη.
That woman is very smart.
The word "εκείνη" in this sentence serves to refer to a specific day in the past, demonstrating its use in temporal referencing.
Θυμάμαι εκείνη την ημέρα σαν να ήταν χθες.
I remember that day as if it were yesterday.
Here, "εκείνη" is used as a personal pronoun representing a female subject being spoken about.