This is the 1160th most frequent German word.
eines
"Eines" is the genitive singular form of "ein" (a/an/one) in German, meaning "of a/an/one."
Here, 'eines' is used as the genitive form of 'one' (from 'eins'), indicating possession or relationship in the phrase 'eines der schönsten Bilder', meaning 'one of the most beautiful pictures'.
Dies ist eines der schönsten Bilder, die ich gesehen habe.
This is one of the most beautiful pictures I have seen.
In this sentence, 'eines' is used as a possessive pronoun in the genitive case, meaning 'one day', where 'eines Tages' translates directly to 'one day'.
Eines Tages werde ich alles verstehen.
One day I will understand everything.
Here, 'eines' is a genitive case modifier for 'Haus', meaning 'of a house'. It shows possession, as in 'the door of a house'.