# keeping steadfast love for thousands

"faithfully loving thousands"

# thousands

"thousands of generations" or "the thousandth generation". This refers to a great number of people. 

# he will by no means clear the guilty

"I will by no means clear the guilty" 

# will by no means clear the guilty

"will certainly not clear the guilty" or "will certainly not say that the guilty are innocent" or "will certainly not free guilty people"

# He will bring the punishment for the fathers' sin on their children

"He will punish the children for their fathers' sin". This phrase does not mean that a child is necessarily punished for the sins of their parents. Many scholars believe that this passage indicates that a parent's sins will have consequences that will affect their children and grandchildren.
 
# their children

The word "children" refers to sons and daughters.