Q:

What does ppm/K correspond to?

I have a precision resistor 10 ohm and 5ppm/K. Does it mean that on delta 1K it will jump up/down 5 ppm of 1 ohm or 5ppm of resistor value - 10 ohms?
I think that it corresponds to resistor value. But Im not sure 100%.

A:

5ppm/K means that the resistance will change by 5 parts per million per 1 Kelvin change in temperature.
The datasheet for your resistor should give the baseline temperature, but it's probably 20C (roughly 293K).  So, if the temperature of your resistor is actually 300K (27C) then it's resistance will be 10 * (1 + (7 * 0.000005)) = 10.00035R.

