# all the nations
"the people of all the nations"
# have drunk the wine of her immoral passion
"have become sexually immoral like her" or "have become drunk like her in sexual sin"
# her immoral passion
Babylon is spoken of as if it were a prostitute who has caused other people to sin along with her. This may well have a double meaning: literal sexual immorality and also the worship of false gods.
# merchants
A merchant is a person who sells things.
# from the power of her sensual way of living
"because she spent so much money on sexual immorality"