This is the 826th most frequent Czech word.
jejích
"Jejích" means "their" (possessive, plural).
In this sentence, 'jejích' refers to 'their' in a feminine plural possessive context, specifying 'friends' belonging to multiple females.
Viděl jsem jejich auto a její dům, ale jejích přátel jsem nepoznal.
I saw their car and her house, but I didn't recognize her friends.
In this context, 'jejích' indicates possession by 'her friends', correlating to a plural group.
Překvapilo mě, že její návrhy byly podobné jejích přátel.
I was surprised that her proposals were similar to those of her friends.
Here, 'jejích' stands for 'her' and modifies 'parents', indicating something belonging to a single female entity.