From publisher blurb:
New Class Archetypes and rules to help you slay giants in your Storm King's Thunder campaign!
Face titanic enemies and win with these eleven new subclasses. Unleash your rage with twin weapons with the Path of Whirling Steel, stand fast against deadly foes with the Sentry martial archetype, swear to protect the weak with the Oath of the Bastion, and sell your soul to Bahamat (or Tiamat) with the Great Wyrm pact. And more!
Also included is a table of giant themed trinkets, a handful or magic items inspired by giant stories of sold, and some spells for funsies.
Last but not least, for the Dungeon Masters there's optional rules for attacking limbs, so your players can't kill giants as easily by stabbing them repeatedly in the ankle.