The quotation in this question comes from Chapter 11, which indicates a shift in the novel as the narrator urges the reader not to focus on the lovely African landscape and beautiful nature that it boasts, but to reflect on the massive problems in South Africa that threaten to destroy it and tear it apart. The full quote reads as follows:
This is no time to talk of hedges and fields, or the beauties of any country... Cry for the broken tribe, for the law and the custom that is gone. Aye, and cry aloud for the man who is dead, for the woman and children bereaved. Cry, the beloved country, these things are not yet at an end.
The quote as a whole therefore calls the reader to think about the ways in which the massive changes in South Africa are having incredibly negative consequences, resulting in "the broken tribe" and lost customs and laws, and the loss of life. The dire poverty that the reader has already been exposed to in the big cities in South Africa, and the terrible prejudice and suffering that occurs there, indicates that this novel is more of a lament about what is happening in South Africa than anything else. "These things" therefore refers to this suffering, but, given this quote's position in the novel, it also foreshadows the death of Absalom later on in the book.