I haven't seen the show for a long time but the symbols are clear:
Lex president: This symbolizes Lex's ambition. The reason he came to see Cassandra is because he believes he has a destiny to fulfill
Lex: Signs I don't want to ignore.
Cassandra: what kind of signs
Lex: I live when I should have died. (...)
IIRC, at that point in the series, ...
At the end of the episode, the president gives a speech in which she mentions how Oliver Queen, the Green Arrow sacrificed himself in the fight to save the Universe. This speech treats him as a well-known hero, so it seems that Oliver did exist in this new Universe up until the same time he died in the original Universe. Note also that they have his costume ...