Multipliers

Melee Multipliers are increased amount of damage a unit does with melee attacks to a certain type of unit. So if a unit has a 5x multiplier against heavy infantry then it takes the units base damage and multiplies it by 5 to heavy infantry.

Unites can also have negative multipliers so if a unit has a 0.5 multiplier against villagers then it only does half damaged to villagers.

When hovering over a unit you are considering building the type of unit it says it is good against is what it will likely have a positive multiplier against. So a unit good against calvary will have multipliers against calvary.