This is the 595th most frequent Estonian word.
aleksandr
The Estonian word "aleksandr" is a proper noun and typically refers to the male given name "Alexander."
Here, 'Aleksandr' is used as a proper noun indicating a person's name.
Aleksandr on väga hea sõber.
Aleksandr is a very good friend.
Here, 'Aleksandri' is again in the genitive case to show that the friend belongs to or is associated with Aleksandr.
Nägin eile Aleksandri Austraalia sõpra.
I saw Aleksandr's Australian friend yesterday.
In this sentence, the name 'Aleksandr' is in the genitive case, 'Aleksandri', to indicate possession.