The Superhero Database Classification number, or SHDB Class, is a number that represents the overall 'power' of a character. All traits of a character are used for calculating the Classification.
What it DOESN'T mean
This doesn't mean that a higher class would always beat a lower class character. But the bigger the difference in Class is, the more obvious it is who'll win in a fight.
How is this calculated
( INT^1.3 + (STR*0.5 )^2 + (SPE*0.5)^2 + DUR^1.6 + (POW + (SPS*SPL))^2 + COM^1.8 ) ^ TIER
Super Power Score and Level
Every Super Power has a score (SPS) that is used to calculate the Class. Each Super Power also has 3 levels (SPL). The level is set when connecting that Super Power to a character. The level determines the final score, of the Super Power, being used in the calculation.
...oneshotted Galactus:
Everbody knows that In the mainstream Marvel Universe, Galactus is incredibly powerful and very difficult to harm physically.
BUt the thing about "Heroes Reborn" it's that actually is an "alternate reality" created by the villain Mephisto. In this reality, Hyperion, is the leader of a government-sanctioned superhero team. When Galactus threatens Earth, Hyperion, driven by a personal vendetta for the destruction of his homeworld, obliterates Galactus in a brutal fashion ... Hyperion appears to definitively kill Galactus. The story shows Hyperion speeding through Galactus' head in a violent manner) and in this reality other "heroes" are shown demonstrating extreme feats of power (like Thanos with the infinity gauntlet being defeated by a single hero.. the copy of Wonder Woman having defeated Knull etc..) this denotes that Galactus has indeed died.
It's a shocking moment that highlights the differences between this alternate reality and the regular Marvel Universe. While it goes against the usual portrayal of Galactus' durability, it serves the story's purpose of establishing Hyperion's ruthlessness and setting the stage for a different kind of superhero dynamic.