By default, Transmit shows two file browsers side-by-side. However, most commands can only be applied to one file browser or the other at any given time. The file browser that will receive the next command is said to be "focused".
The currently focused file browser will show a highlighted segment in the path bar.
In this example, the file browser on the right has focus.
You can focus the other file browser by clicking anywhere inside it.
Alternatively, choose View > Focus on Local or View > Focus on Remote.
Switching between one and two file browsers