This is the 32nd most frequent Estonian word.
üks
"Üks" means "one" in English.
In this sentence, 'üks' means 'one' as a numeric quantifier used to specify the singular item.
Üks õun on punane.
One apple is red.
In this sentence, 'üks' emphasizes or highlights the quality of being a good friend, functioning almost as 'a certain' in its meaning.
Ta on üks väga hea sõber.
He is a very good friend.
Here, 'üks' is used in the phrase 'üks kord', meaning 'one time', indicating a single instance.