The general flow of the game is using your character's skills to defeat monsters to obtain items. When properly equipped, items can add a variety of stats, properties, and effects to your character, making it easier to defeat monsters.
Strength, Dexterity, Vitality, and Energy are your character's base stats. You can add points to these manually as you level up or complete certain quests. Some items have Strength and/or Dexterity requirements before they can be equipped. The All Attributes stat on some items increases all of these stats.
Stamina allows your character to run. You move faster but lose the ability to block with a shield. Stamina Drain items affect how much stamina you lose as you run. Heal Stamina changes the amount of stamina you have as you hit. Some monsters deal Stamina damage as they hit you.
As long as you have Life, your character is still alive. Items can add Life, Maximum Life, and Life (Based on Level). Replenish Life restores lost Life to your character slowly over time. When affectd by Open Wounds, life decreases over time. Items with Life Stolen can restore Life based on your attack damage. Items with Life After Each Kill restore Life as you kill enemies.
Mana is a requirement for using some Skills. Items can add Mana, Maximum Mana, and Mana (Based on Level). Regenerate Mana restores used Mana slowly over time. Damage to Mana allows you to restore lost Mana by taking damage. Mana Stolen can restore Mana based on your attack damage. Items with Mana After Each Kill restore Mana as you kill enemies. Some monsters can deal Mana damage using up some of your Mana as they hit you.