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.
However, please note Sentry comes back and knocks him out.
Still, the battle was closer than HE vs. Galactus in FF #174, were Galactus basically stompted.
Also, (though the actual battle was off-panel) Spider-Man said Sentry stalemated Galactus. Even though that seems a bit ridiculous, the word 'stalemate' suggests that it was closer than HE vs. Galactus.