The slope of this graph is I/V. Rearranging Ohm's Law:

V = IR  —>  R = V/I

So R = 1/slope = 1/.22 = 4.5Ω

Test it with your meter. Turn the knob to the 200 in the Ω section of the dial.
Touch the probes to points 20 cm apart on your wire. You should get about 5 Ω. Cool huh? Try sliding the probes along the wire and watch how the resistance value changes with length. Got it?