Objective Raid is basically like Rush from Battlefield. You must detonate an objective and protect it for a set amount of time for it to explode. There is always 2 targets to detonate if you're on the attack team. If you're on the defending team you must make sure no one touches the objectives, and disarm them if they do.
This achievement only requires about 2 minutes of gameplay in Objective Raid for it to pop. Also if you continue to play for another cumulative of 2 hours, you will get the 2nd variant of this achievement.