This character is a Other Symbol and is commonly used, that is, in no specific script.
The glyph is not a composition. Its East Asian Width is wide. In bidirectional text it acts as Other Neutral. When changing direction it is not mirrored. U+1F306 offers a line break opportunity at its position, except in some numeric contexts.
The CLDR project calls this character “cityscape at dusk” for use in screen reading software. It assigns these additional labels, e.g. for search in emoji pickers: at, building, city, cityscape, dusk, evening, landscape, sun, sunset.
This character is designated as an emoji. It will be rendered as colorful emoji on conforming platforms. To reduce it to a monochrome character, you can combine it with Variation Selector-15: 🌆︎ See the Emojipedia for more details on this character’s emoji properties.
The Wikipedia has the following information about this codepoint:
Dusk occurs at the darkest stage of twilight, or at the very end of astronomical twilight after sunset and just before nightfall. At predusk, during early to intermediate stages of twilight, enough light in the sky under clear conditions may occur to read outdoors without artificial illumination; however, at the end of civil twilight (when Earth rotates to a point at which the center of the Sun's disk is 6° below the local horizon), such lighting is required to read outside. The term dusk usually refers to astronomical dusk, or the darkest part of twilight before night begins.