What makes up a character?
A character in Simply Roleplaying is made up of several different pieces. If you're creating a character for the first time, you may want to check out the walkthrough in character creation. The content on this page and that page are almost the same, this one is just aimed at breaking everything on your character sheet down while that page is aimed at walking you through setting it up.
Your level represents, generally, how strong you are. You add this to your attributes to determine the total number of dice you can roll from your skills, legacies, and backgrounds.
Health and injuries
Health is how much damage you can take before you suffer an injury. Injuries take time to recover from, and if you take too many you'll be defeated. Injuries are both a box and a line describing the harm you took -- only the box matters for gameplay purposes, the text is just to remind you what happened so you know when it makes sense to recover from it.
Attributes are broad categories which represent your strengths and weaknesses-- your physical strength, ability to quickly respond, willpower, and more. Any time you make a test, it'll test a specific attribute and you'll add that attribute to your level to determine how many dice to roll. You also have passive attribute scores that you use instead of dice for when you respond reflexively to that attribute being tested.
Skills, legacies, and backgrounds
Skills, legacies, and backgrounds are the individual pieces that make up who you are and what you've learned. Skills describe what you know how to do: anything concrete that you can get better at, given practice. Legacies describe your reputation: your values, the factions you've allied with, and the deeds you've done. Backgrounds describe you: they're built from Skills and Legacies put together and summarized.
Special abilities and ability points
Special abilities are the unique and cool things your character can do. Casting magic, building inventions, or memorizing crucial details all can go here. Ability points are a pool of points that you can spend on doing special ability stuff.
Your inventory is filled with all the stuff you own. Anything you can use to accomplish a task usually has tags that describe its properties. Items in your inventory are either equipped or not-- equipped items are usually visible and easy to get to, unequipped items are stored away somewhere on your person.
Your companions are anyone else who travels with you, but doesn't need a full character sheet to represent them. A helper offers you the support of their skills. An ally has attributes, damage, and inventory of their own, but shares your level, injuries, skills, legacies, backgrounds, and special abilities.