What does ps mean? I’m used to the US standard of using bhp for brake horsepower. How do I convert ps values to bhp?

First of all bhp and ps are slightly different animals. Bhp or brake horsepower is a calculation where the engine horsepower is measured with no load from a chassis or any accessories attached to the engine whatsoever. It’s also called gross horsepower. PS, on the other hand, is a measurement of net horsepower. It’s horsepower calculated with the engine installed in the vehicle, complete with accessories and ductwork. So you can’t really convert one measurement to the other with a simple formula.
                      

          back

 
 

 However, just to give you a better idea on what "ps" stands for, we can talk a little more about horsepower. Just as there are different ways of measuring temperature, as in Centigrade or Fahrenheit, you can measure the power of your engine in several ways, too.

Horsepower is simply your engine’s ability to move mass over a certain amount of time. If you want to be technical about it: one horsepower can lift 33,000 pounds up one foot in one minute. And that’s the measure of horsepower you’re familiar with, the one used in the U.S., and it’s the standard set by the Society of Automobile Engineers, which is why it’s also called SAE horsepower. The ps you’re asking about is short for the German word Pferdestarke, the term for metric horsepower, also known as DIN horsepower. DIN is short for Deutsche Industrie Normen which simply translates to "German industrial standard".

So, in summary, hp is the U.S. standard for horsepower, while ps is the standard in continental Europe.

If you want to dazzle your friends, you can say that one horsepower is equal to 1.0139 ps, making SAE horsepower roughly 98.6% of the metric DIN measurement.