The combat in the game will be divided by Turns. Each unit present in battle (both player characters and enemies) will be allowed to take action once per Turn, from the fastest to the slowest (how fast a character is is determined by its Agility).
When taking action a character can either Attack, use a Spell, use a Consumable or Skip their action.
Simple mockup of how it will look in game.
After every character has acted the game will progress into the next Turn where characters take action again from the fastest to the slowest. This goes on until either all player characters die or all enemies die.
When combat ends a feedback screen will be shown and rewards will be given to the player.
To prevent the combat from being a damage race there will be status effects, buffs and debuffs. Some status effects prevent units from acting, making them skip their turn. Some buffs / debuffs can increase / decrease the agility of units, causing them to possibly move earlier / later next turn.