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.
The only characters in DBS who can beat Infinite Zamasu are Zeno (he proved it), most likely Super Shenron (he can grant any wish), and "maybe" (but you're gonna fail proving it with feats / statements) the angels.
Anybody else - especially "only" 3-dimensional fighters like those on the team (Goku / Beerus / Jiren) who are only "flying bricks" just lack the necessary multiversal HAX to get rid of Infinite Zamasu.