The dining room curtains add color to the room, provide privacy, and improve acoustics. The window covering generally consists of two pairs of curtains.
A pair of curtains provide privacy while retaining light. For example, net curtains, inbetweens, or thin Roman blinds.
The second pair of thicker curtains are for the evening. In general, a thick inbetween is enough in the dining room, but you can also opt for a thicker curtain.