This is an extraordinary movie about... About what? Different people will give different answers. The story takes place in Hungary near the end of WWII, during the German occupation of Hungary, his ally. Everybody faces the same problem: would you survive the war, and how? Would you die from hunger, shoot by Germans, hit by a British or Soviet bomb? And some people face additional problems: they are Jews.
Some people face a problem of a different nature: to keep their integrity, decency, honesty. This is not easy even if you a ready to die for this, because if you a really decent, you will try to help people who are in a worse position than you. In practice this meant doing good deeds as a part of underground resistance; and appear to be not quite scrupulous person to others. The main story line is driven by this problem.
The title, "The fifth seal" (a quote from "Apocalypse") hints at the only solution: you have to deal with this till the end (of the world in "Apocalypse", the end of the war in the movie).
One of the characters often says "And now he is not going to die?" It seems that the meaning of this is not immediately transparent, but this is another central part of the movie. To explain this would be a spoiler.