U+254F Box Drawings Heavy Double Dash Vertical

The Wikipedia has the following information about this codepoint:

Box-drawing characters, also known as line-drawing characters, are a form of semigraphics widely used in text user interfaces to draw various geometric frames and boxes. These characters are characterized by being designed to be connected horizontally and/or vertically with adjacent characters, which requires proper alignment. Box-drawing characters therefore typically only work well with monospaced fonts.

In graphical user interfaces, these characters are much less useful as it is more simple and appropriate to draw lines and rectangles directly with graphical APIs. However, they are still useful for command-line interfaces and plaintext comments within source code.

Some recent embedded systems also use proprietary character sets, usually extensions to ISO 8859 character sets, which include box-drawing characters or other special symbols.

Other types of box-drawing characters are block elements, shade characters, and terminal graphic characters; these can be used for filling regions of the screen and portraying drop shadows.