With the recent updates to the character builder, we are working to update our documentation. The Article below has not yet been updated, so there may be some differences from the current experience.
The sheet has different sections under the character header that present information about different aspects of the game.
Abilities, Saves, Senses
This screen shows your Ability Scores and modifiers, Saving Throws and modifiers, and Senses, which include your Passive Perception, Investigation, and Insight scores.
Limited Use
This section aggregates all your traits, features, or abilities that have a reset condition, such as Short Rest, Long Rest, or Dawn. The intent is to collect special abilities you can't use at will in one place so your options are more visible.
You can track the uses of such abilities in this section by clicking the appropriate buttons.
The Short Rest, Long Rest, and Dawn buttons at the top of the section can be used to reset all the relevant abilities at one time. Hit Dice can also be tracked as part of a Short Rest.
Skills
This screen displays all of your skill modifiers, including Proficiencies, Expertise, Jack of All Trades, etc.
Actions
In this section, you'll see your list of available Actions, Bonus Actions, Reactions, Other "Special abilities tied to actions, like Sneak Attack. Under "Actions," the list will include equipped weapons and any spell attacks available to you. You can also Customize many of these items by clicking on any individual action or weapon and then clicking on "Customize."
Inventory
In this section, you can alternate between the "My Inventory" and "Party Inventory" tabs, and and add, equip, and attune to items in the "My Inventory" list and "Manage Inventory" window. You can also see encumbrance details, note other personal possessions, and manage your currency in this section.
Spells
In this section, you can manage your spell slots, use the Manage Spells window to add known spells and to prepare spells, and view your prepared spells for table play. Spells that appear here can expand to display the spell's details and quick-info such as the Save DC and type.
Speed, Defenses
This screen displays your Walking and other speeds, as well as your Defenses, which include your Resistances, Immunities, and Vulnerabilities. By clicking Manage Defenses, you can Customize and add new Resistances, Immunities, and Vulnerabilities.
Features & Traits
This section is a reference that displays all the various Class Features, Species Traits, and Feats your character has. By clicking Manage Feats, you can Customize further and add new Feats.
Proficiencies & Training
This section displays your proficiency modifier, as well as all your character's Armor training, Weapons and Tools proficiencies, and Languages known. By clicking Manage Proficiencies, you can Customize further and add each of the aforementioned items to your list.
Background
This section displays your chosen Background and Ability Score Improvements, as well as any personal Characteristics and Appearance notes you wrote down in the Character Builder.
Notes
You can add notes in predetermined sections (Allies, Enemies, Backstory, and Other) or create freeform notes that come up during play here.
Extras
Creatures: This section will display the creatures you character has available to them.
Edit Character on Website: This link takes you to the D&D Beyond website so you can edit the character further.