This character is a Other Symbol and is commonly used, that is, in no specific script.
The glyph is not a composition. It has no designated width in East Asian texts. In bidirectional text it acts as Other Neutral. When changing direction it is not mirrored. U+1F3DF offers a line break opportunity at its position, except in some numeric contexts.
The CLDR project calls this character “stadium” for use in screen reading software.
This character is designated as an emoji. It will be rendered as monochrome character on conforming platforms. To enable colorful emoji display, you can combine it with Variation Selector-16: 🏟️ See the Emojipedia for more details on this character’s emoji properties.
The Wikipedia has the following information about this codepoint:
A stadium (pl.: stadiums or stadia) is a place or venue for (mostly) outdoor sports, concerts, or other events and consists of a field or stage completely surrounded by a tiered structure designed to allow spectators to stand or sit and view the event.
Pausanias noted that for about half a century the only event at the ancient Greek Olympic festival was the race that comprised one length of the stadion at Olympia, where the word "stadium" originated.
Most of the stadiums with a capacity of at least 10,000 are used for association football. Other popular stadium sports include gridiron football, baseball, cricket, the various codes of rugby, field lacrosse, bandy, and bullfighting. Many large sports venues are also used for concerts.