Golz is the Russian general responsible for leading the Republican offensive, of which Robert Jordan's mission is a part, though he insists it's not "his attack." Robert Jordan lets us know that he's a good general, which isn't that common the Republican side, but he's usually given more menial tasks by the higher-ups.
Like some of the other characters, Golz is a fatalist with a keen sense that a lot of what happens in the war is just outside of one's control. After learning that the fascists are waiting for it, he accepts that his attack is doomed with resignation, and in French (naturally): Rien a faire. Rien. Faut pas penser. Faut accepter (42. 174) – that's "Nothing to do. Nothing. Must not think. Must accept." But lest you think Golz is always serious, we should mention he likes jokes. As he would say, "he's so serious is why he can be funny."