Is this a clip-on lens for my phone?

No — and this is worth being clear about. It is a replacement part fitted inside the phone during a repair. It does not attach to the outside of a handset and it does not add any capability the phone did not already have. It restores a camera that has stopped working correctly.

It identifies which camera in the rear array the part belongs to — the 2X designation is the telephoto camera — the one used for optical zoom. Check which of your cameras is faulty before ordering, because the parts are not interchangeable between them.

Are hazy photos a camera fault?

Usually not. If the camera still focuses and shoots but photos are hazy or flared, the outer lens cover glass is cracked — a far cheaper part than the camera.