In this verse, David asks the Lord for protection; partly corresponding with Psalm 140:1b. The last sentence explains the bad intentions that David’s enemies have. Literally it says that they want to cast away
David’s footsteps. That means they want to trip him up and make him fall. They are eager for his downfall.
4 Guard me, O LORD, from the hands of the wicked; preserve me from violent men, who have planned to trip up my feet.