Nikon D3200 AE-L/AF-L Button: If you prefer your subject to be off-center, press this button to focus on your subject in the center of the frame. This allows your camera to keep them in focus when you position them.
Exposure Lock (AE-L Button) : How to Use the Exposure Lock
Exposure Lock (AE-L Button) is the abbreviation stands for Automatic Exposure Lock. It is useful using automatic and semi-automatic shooting modes.
Nikon D3200 Beginner DSLR: Guided Tour
Nikon D3200 Guided Tour: everything you need to know if you are considering or have recently purchased the D3200
Nikon D3200 Tutorial - How to Set Up Nikon D3200 Menu Guide Tutorial