Does using a Videocard lessens the load of the cpu in gaming

for now im using a pentium g2020 cpu and intel hd graphics 2500
if i install a decent graphics card will the cpu load decrease in gaming

A nice new GPU will help very much so. Adding more ram will help with overall performance as well. The GPU is designed to do the work that is normally done by the onchip video device so yes, it would be a massive advantage. Don't expect it to be a miracle though, the CPU isn't a huge one, you might want to look at getting the new G3258 Pentium dual core, a VERY good CPU ARK | Intel® Pentium® Processor G3258 (3M Cache, 3.20 GHz)
You would just need to make sure your MB would handle it. In the US the cost of this CPU is $70.00 approx.

Hope that helps. :)

yes i plan to upgrade this later but an i5 processor. the g3258 is overpriced here yet good performance when oc almost i3.
thnks for your confirmation