What is the symbol that is near the battery life that is a lock with a circle around it?

Orientation lock

Portrait orientation lock. To turn off, doublt-tap the home button, swipe the list at the bottom to the right, tap the left-most icon (left of the music controls).

Then what?

The left most icon was the speaker icon?

The left most icon was the speaker ?

How do I unlock it?

1. Double-tap the home button
2. Swipe the list at the bottom to the right until you see the image below
3. Tap the left icon (see red box in image below)

This will unlock the portrait orientation lock and allow you screen to rotate sideways again (to landscape position).