What is the meaning of the phrase "to So-and-so, and So-and-so, and So-and-so, one-third of my wealth, just as my children inherit, with the male receiving the share of two females" in the grandfather's will? And does allocating one-third to them mean they are entitled to it, or do they share their portion with the paternal uncles?

The intention of your grandfather's will is that you get one-third, to be divided among you "for the male, a share equal to that of two females." His statement "like so" refers to the method of division, as evidenced by his subsequent statement, "for the male, a share equal to that of two females." The will is valid because it does not exceed one-third, and you are not among the heirs.