Arcana Coelestia #486
486. Verse 4 And the days of Man after he beget Seth were eight hundred years; and he beget sons and daughters.
'Days' means periods of time and states in general. 'Years' means periods of time and states in particular. 'Sons and daughters' means the truths and goods that they perceived.
Daniel 7:27
27
The kingdom and the dominion, and the greatness of the kingdoms under the whole sky, shall be given to the people of the saints of the Most High: his kingdom is an everlasting kingdom, and all dominions shall serve and obey him.