What does "Pins are on 0.17" centers" mean?
No.

Centers, in this context, means that the pins are spaced at 0.17" intervals.

Basically, the "center" of each pin is 0.17" from the previous pin's center. 

As such, "on x" centers" can be translated as "the center of each pin is x from the center of the previous pin" 

For a component to work in a common solderless breadboard, the pins have to be spaced 0.100" apart, in other words, they have to be on 0.100 centers (or some integer multiple of 0.100", such as 0.200" or 0.500" centers).