What is the meaning of 下駄?

geta: a kind of wooden clog with at least one, more commonly two, stilts or “teeth

the geta symbol, (Unicode value 3013): a typographic mark indicating unavailability of a glyph, such as when a character cannot be displayed on a computer; so called for the similarity to a geta clog footprint

a stone placed not adjacent to the opponent's stone, but in such a way as to block the opponent's formation from escaping

Source: wiktionary.org