Jaggery or Gur (Hindi), Gul (Marathi), Bellam (Telugu), Vellam (Tamil), Sharkara (Malayalam) or Bella (Kannada) is basically unrefined sugar that’s prepared by boiling natural sugarcane juice till it solidifies and then put into blocks. The colour can range from golden to dark brown. Gur is the healthiest natural replacement as unlike sugar, this doesn't go through multiple processing stages.
While one can definitely replace the white sugar with jaggery, a daily consumption level of 10gms is what is advised by nutritionists.