Yes, you certainly CAN watch 2D (normal) content as you would expect in any normal TV.
3D content displays as two images on TV - left-right or top-down. The glasses combine the images for your eyes and show you the 3D picture.
There is a setting to enable or disable 3D, and choose which setting to choose (up-down or left-right).
If you set TV to 3D and content is 2D, images will look mixed-up. If you have 3D movie and set TV to 3D but not use glasses, you will see two images.
If you have 2D content (99% of the movies and shows today are 2D), and you don't enable 3D setting on TV, and don't use glasses, you will see beautiful 2D picture as you would expect from a high-quality HDTV from Sony. I love this TV.