These are your expected damage per hit and your damage per second values.

These values are calculated from the server side values given by Dead Frontier. They are periodically updated from Dead Frontier and verified. You can access the JSON file that these values are stored in here.

The left side

The value on the left is calculated using the following equation,
1 + (damagePerHit * (boostBonus + EXBoostBonus + implantBonus + clanBonus + 1))
damagePerHit comes from the JSON file, boostBonus is calculated from your characters drugs(Ultra Boost, Mini-Boosts, etc...), EXBoostBonus is calculated from your characters EX drugs, implantBonus is calculated from equipped implants added together, and clanBonus is your clan's damage value.
The reason that you add one to the boostBonus, implantBonus, and clanBonus is so the multiplication is done as 100% of your damage with the added bonus percents. The reason that you start at positive one is so weapons cannot do zero or negative damage.
damagePerHit for burst-fire weapons is the combined value of every shot from a burst.

The right side

The right side value is calculated using the previous value multiplied by pellets and hitsPerSecond from the JSON file.
damage x pellets x hitsPerSecond

Bursts

Weapons with bursts handle their damagePerHit value differently. Instead of damagePerHit being a value per pellet, it's the combined value of the burst shot.
An example from the Impaler Crossbow,
// JS Notation
let damagePerHit = 60;
let calculatedDamagePerHit = 0;
for(let i = 0; i < parseFloat(weapData["selective_fire_amount"]); i++)
{
    calculatedDamagePerHit += damagePerHit * weapData["selective_fire_split"][i];
}
return calculatedDamagePerHit;