This is the 1093rd most frequent Turkish word.
birbirine
"Birbirine" means "to each other" or "to one another" in English.
Here, 'birbirine' means 'each other,' denoting mutual assistance between the two friends.
İki arkadaş birbirine yardım etti.
Two friends helped each other.
In this sentence, 'birbirine' signifies mutual similarity among multiple items or individuals.
Hepsi birbirine çok benziyor.
All of them look very similar to each other.
Here, 'birbirine' is used to indicate reciprocal action (greeting) between two neighboring parties.