Those are formatting characters. ¤ (Unicode character 00A4) specifically means "end-of-cell".

This is the end-of-cell marker. It is a little like the paragraph mark in that it contains paragraph formatting for the last (or only) paragraph in the cell, but it also holds formatting for the cell.

The same mark at the end of each row is the (wait for it) end-of-row marker, which serves a similar purpose with regard to row formatting.

This is Microsoft Word's way of indicating a cell in a table. These are displayed only on screen and get never printed. This holds also for the other weird symbols you see in that screenshot. You can hide them in the format section of the command ribbon.