On HOK Global, "tank comps" usually mean one of two things:
1. Double frontline: a tank support (Dun, Sakeer) + a tanky clash laner (Lapulapu, Augran). This is the most common setup. The frontline is durable but not unkillable.
2. Triple frontline: double frontline + a tank jungler (Athena, Liu Bei built tanky). This is rarer but much harder to deal with. If the enemy has three tanks, you need to itemize correctly or you simply can't kill them.
The mistake most players make against tank comps is trying to burst through the frontline. You can't. Tanks are designed to absorb burst. What kills tanks is sustained damage, armor penetration, and %HP damage.