Arsenal. Here you can change everything about your weapons and your character.
You can buy whole, new warframes If you are not satisfied with your current.
You can socket "Cards" into your weapons and warframe. Cards are the essence of warframe. Your entire time playing this game is to get the best cards and level them up accordingly.
Cards are all either flat-out stat bonuses such as extra shield, HP or damage but most of them are skill-cards, allowing you to put them on your warframe to perform them in battle.
Choosing the right ones is absolutely critical to creating a solid build.
The game also allows you to change your apperance.
It does this mainly through different available colors.
You have a small cache of free ones but to get the "Shiniest" kinds, you'll need to pay with real money.
Everything can be recolored. Even your sword.
You can also buy a small "Pet" called "Sentinels". They aid you in combat..
In a variety of ways.
From vaporizing your opponents..
To making you invisible.
It's also the place of your inventory. As I am on a new account, there's not much present.
There are also the rather new addition of "Mods".
They are as of right now, almost entirely vanity though.
If you recently played a game, It may be confusing but the game has already automatically matched you up to play another session with the same people you played with previously.
The game calls it "Sessions". And to leave one, simply press (ESC) and confirm.
You know you are alone without any timers ticking when this screen is present.
Here, you can also see your current stats.
The store will almost be a guaranteed place you'll visit since you start out with 50 plat. That's roughly about 4-5$ free in-game currency.
Here, you can buy card packs, warframes, weapons, colors, sentinels.. Really anything you can think of
It all however, requires Platinum. An in-game currency only purchaseable with real currency.
The variation of things to buy however, is nothing short of staggering.
Character accessories to alter the apperance of your Warframe along with icons for fellow players to view at your profile are all available for purchase.
If you do not partake in the real money store, you will need to spend a lot of your time here, in the Foundry.
Here, you will need thousands of different materials to be able to create even the simplest of items. You get these materials by doing missions and boy will you have to do alot of them. You'll also need special recipes that can be exceedingly rare.
In the codex, you'll find the artistical side of Warframe.
Lore about the warframes..
A card collection section..
A dedicated art gallery..
A lore section..
And much more. There's also tons of information available on the game wiki.