Status ailments can be confusing. Below is a list of Status Ailments and effects for Octopath Traveler: Champions of the Continent.

Bleed/Poison: Unit loses a portion of their max HP at the end of their turn. Bleed does more damage when enemy is weak to physical (debuff PDEF) and when your PATK is higher (buff PATK). Poison does more damage when enemy is weak to elemental (debuff EDEF) and when your EATK is higher (buff EATK) (/u/LadyNarayan). Both Bleed and Poison will do more damage when the enemy is Broken. Some units have passives that proc if the enemy is poisoned/bleeding. 

Blind: Reduced accuracy for physical attacks.

Break: Not a status ailment but enemy receives 200% more damage from all sources and is unable to perform any action on the turn they’re broken and the following turn. When Break ends, said enemy is the first to take action, even if you use high-priority skills.

Can’t Switch: You cannot switch this character.

Dread: Inflicted by Pardis and select few bosses. Same effect as Terror. There is an accessory that nullifies Dread.

Paralyze: Unit has a chance to not be able to act.

Second Wind: Not a status ailment, but it’s SP regen.

Silence: Unit is unable to use 1 random skill.

Sleep: Unit is unable to take any action until hit by an attack. Unit can wake up naturally once the status expires.

Terror: Unit cannot use BP and cannot naturally gain BP.

Vim and vigor: Not a status ailment, but it’s HP regen. 

Weakness: Unit SP cost doubles.