When things fall into place, they happen in a satisfactory way, without problems.

If you plan the project well, then everything should fall into place. 如果你项目计划得当，那么一切都应有条不紊地进行。

When events or details that you did not understand before fall into place, they become easy to understand.

Once I discovered that the woman was his sister, everything fell into place. 一旦我发现那个女人是他姐姐，一切都变得清楚起来。