What does Jailbreaking a iPhone 5 let you do?

I want to know what dose it let you do

Get free apps, free in app purchases, download music from iphone into library, customize it, add themes.

Get any paid apps for free better features such as andriod lock etc

1.Free apps.
2. No need to buy music.
3.Transfer stuff via bluetooth(incl.music).
4.Add widgets(like androids)
5. If you locked onto a specific carrier, you can change.
6.Using USB OTG (connecting you pendrive to your iPhone/iPad) to act as an SD Card.

You can't jailbreak an iPhone 5. There's no released jailbreak for an apple device after the iPhone 4s. But if there we're a jailbreak for it, it allows you to:
Download 3rd party apps
More customization options (themes, fonts, etc)
Removes the safeguards against piracy(free music, movies)
Ability to download free apps and get free in app purchases.

There's more stuff, but that's the general stuff

It is simply called ''BLACK MARKET''.

where pro/full apps and other media can be downloaded for FREE.