Question

What unit the size is displayed on info window on photoshop cs6?

Answer 1

It depends on user preference... There are 7 type of units available in photoshop...

1. Pixels
2. Inches
3. Centimeters
4. Milimeteres
5. Points
6. Picas
7. Percent

I'm not sure about which one is default...

How to change default unit?
1. Go to Edit > Preferences > units and Rulers... or press ctrl + k
2. In unit section Change unit to pixels

So in simple terms if user will select pixels than units will be in pixels in info window and if user will select centimeters than units will be in centimeters and so on... 

Answer 2

the default is pixels