A few concepts of defensive and offensive ship stats explained in a few words:

𝑯𝑰𝑻𝑷𝑶𝑰𝑵𝑻𝑺 - Every ship or structure has a pool of hitpoints that is reduced through weapons effects until it is depleted and the ship is sunk or the structure is destroyed.

𝑬𝑽𝑨𝑫𝑬 - Basically a hit or miss stat, 50% evade means that 50% of the weapons fire will miss your ship entirely. In short, not getting hit is better than any armor. There's a little more to it
though - If the weapon firing at you has an accuracy above 100%, it begins to compensate for evade.

𝑫𝑬𝑭𝑬𝑵𝑺𝑬 (𝑹𝑬𝑺𝑰𝑺𝑻𝑨𝑵𝑪𝑬𝑺) - Weapons fire that hits your ship after evade is calculated is subject to its defense, which is damage type specific. 50% defense means only 50% of the nominal damage actually hurts your ship.

𝑻𝑼𝑹𝑹𝑬𝑻 𝑫𝑬𝑭𝑬𝑵𝑺𝑬 - This is additional protection against damage from turrets. 50% turret defense means the damage from turret weapons passing through the resistances is reduced by a further 50%.

𝑫𝑬𝑭𝑳𝑬𝑪𝑻𝑰𝑶𝑵 - This basically is a flat value of damage ignored and is applied AFTER evade and resistances and turret defense.
When a 10000 damage weapon hits a ship with 50% armor and 500 deflection, it would do 5000 damage after armor and then 4500 after deflection.
A 1000 damage weapon hitting the same ship would do 500 damage after armor and 0 after deflection. Since the game doesn't want you to take 0 damage, a minimum amount of damage will always get through.

𝑫𝑬𝑭𝑬𝑵𝑺𝑬 𝑩𝒀𝑷𝑨𝑺𝑺 - This is a portion of weapons damage that does not go through defense calculation. This includes both the regular defenses as well as turret defense bonuses. Simply put, 50% defense bypass on a 1000 damage weapon means one half (500 damage) flatly punch through your defenses and the other half (500 damage) are reduced according to your defense and turret defense. Bypassed damage will still be subject to deflection.

𝑫𝑬𝑭𝑳𝑬𝑪𝑻𝑰𝑶𝑵 𝑩𝒀𝑷𝑨𝑺𝑺 - Same as defense bypass really, just affecting deflection, i.e. the portion of weapons damage that does not go through deflection calculation.

𝑨𝑺𝑺𝑨𝑼𝑳𝑻 𝒙𝒚/𝑺𝑰𝑬𝑮𝑬 𝒙𝒚 - whenever you see this, it indicates the effect is limited to either damage to/from ships (e.g. assault deflection) or turrets (e.g. siege deflection).

𝑨𝑺𝑺𝑨𝑼𝑳𝑻 𝑫𝑷𝑺/𝑺𝑰𝑬𝑮𝑬 𝑫𝑷𝑺 - this improves your weapon effects by a flat amount, distributed evenly over your weapons. On a ship with 10 weapons doing 500 damage per second each, an assault DPS of 200 would make each weapon do 520 damage per second to ships (200/10=20) and 500 damage per second to buildings.

𝑫𝑷𝑺 (𝑵𝑶𝑴𝑰𝑵𝑨𝑳) - Nominal damage per second. This is what you dish out. This can be different for ship and building targets.

𝑫𝑷𝑺 (𝑬𝑭𝑭𝑬𝑪𝑻𝑰𝑽𝑬) - Effective damage per second. This is what ends up hurting your opponent, after all of the above calculations. You can receive or deal huge amounts of damage on paper, but with the right setup, only a fraction of it will actually hurt you and reduce your hitpoints.

With thanks to Sarah Gilad (AshleyWilliams of TDAC) for making this!