[HFSS] Explaination on Dipole RAdiation Pattern needed

Hi i've design a 433MHZ dipole antenna using HFSS and simulated the radiation pattern for the E-field for theta=0,90,180,270 and 360 degree. can someone explain to me what does the graph actually represent, why is the pattern is as such? what does the 1.00 to 4.00 is the graph represent?
thank you.