This is the 694th most frequent Latvian word.
aleksandrs
"Aleksandrs" is a Latvian male given name, equivalent to "Alexander" in English.
Aleksandrs is a proper noun used as the subject of the sentence.
Aleksandrs spēlē klavieres.
Alexander is playing the piano.
The word 'Aleksandra' is the possessive form of the proper noun Aleksandrs, indicating ownership.
Tas ir Aleksandra draugs.
That is Alexander's friend.
This uses 'Aleksandram,' the dative form of Aleksandrs, used to indicate the indirect object or recipient in the question.