Those bonuses only apply to level 40 characters that are built with 1 (single) or 2 (dual) classes.
All classes that can cast spells:
Single: +3 DC to all spells
Dual: +1 DC to all spells
Barbarian:
Single: +1 damage reduction, +2 (simulated) strength when raging
Dual: +1 damage reduction
Bard:
Single: +1 to all skills, AC, damage and saves to bard song and curse song
Dual: +1 to skill to bard song and curse song
Cleric:
Single: can heal/harm up to 60% of the damaged hit points (instead of 50%), up to 300 hp (instead of 250 hp)
Dual: can heal/harm up to 60% of the damaged hit points (insted of 50%)
Fighter:
Single: +6 damage with specialized weapon/s
Dual: +2 damage with specialized weapon/s
Monk:
Single: +1% movement speed bonus every 5 monk levels, the base unarmed damage is 2d12 when medium sized and 3d6 when small sized
Dual: +1 movement speed bonus every 5 monk levels
Paladin:
Single: +15 dispel DC (25) to weapons with Holy Avenger
Dual: +5 dispel DC (15) to weapons with Holy Avenger
Ranger:
Single: +3 to favored enemy bonuses
Dual: +1 to favored enemy bonuses
Rogue:
Single: +3d6 sneak attack damage
Dual: +1d6 sneak attack damage
Arcane Archer:
Dual: +1 to enchant arrow feat
Dwarven Defender:
Dual: +2 damage reduction
Pale Master:
Dual: +1 real caster level (extra spells, extra damage, duration, spell penetration, resistance vs dispel)
Weapon Master:
Dual: +1 AB