# The earth

Possible meanings are 1) the people who lived on the earth or 2) "The earth itself." 

# was corrupt

"was rotten" or "was completely evil" 

# before God

Possible meanings are 1) "in God's sight" or 2) "in the presence of Yahweh" 

# and it was filled with violence

"and there were very many violent people on the earth" or "because it was full of people who did evil things to each other"