Depends on what you call a beginner and where you are. In the Netherlands, someone is often called a beginner after following a 5-6 week introductory course, with sessions of 1-2 hours per week. So they have then got about 10 hours of go experience, with some time taken teaching the the rules plus basic tactics (ladders, nets), and the rest spent playing (mostly 9x9 and 13x13). They are then generally about 25 kyu, though talented players may already be 20 kyu, while those slower on the uptake may still be lingering at 30 kyu. And childrens tournaments often even have players in the 35-45 kyu range.

The page on Rating Histogram Comparisons also shows that an AGA 35 kyu is roughly around KGS 25 kyu (and therefore also, presumably, EGF 25 kyu, but the EGF doesn't measure under 20 kyu).

So all in all there is not one clear answer to your question. But roughly I would say that in the AGA system a beginner is probably 35 kyu (which really means something like "in the range 40-30 kyu") and in the EGF system a beginner is 25 kyu (again, this is more something like "in the range 30-20 kyu").