This character is a Otro símbolo 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+23F0 offers a line break opportunity at its position, except in some numeric contexts.
The CLDR project calls this character “reloj despertador” for use in screen reading software. It assigns these additional labels, e.g. for search in emoji pickers: alarma, despertador, reloj.
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.
El Wikipedia tiene la siguiente información acerca de este punto de código:
An alarm clock or alarm is a clock that is designed to alert an individual or group of people at a specified time. The primary function of these clocks is to awaken people from their night's sleep or short naps; they can sometimes be used for other reminders as well. Most alarm clocks make sounds; some make light or vibration. Some have sensors to identify when a person is in a light stage of sleep, in order to avoid waking someone who is deeply asleep, which causes tiredness, even if the person has had adequate sleep. To turn off the sound or light, a button or handle on the clock is pressed; most clocks automatically turn off the alarm if left unattended long enough. A classic analog alarm clock has an extra hand or inset dial that is used to show the time at which the alarm will ring. Alarm clock functions are also used in mobile phones, watches, and computers.
Many alarm clocks have radio receivers that can be set to start playing at specified times, and are known as clock radios. Additionally, some alarm clocks can set multiple alarms. A progressive alarm clock can have different alarms for different times (see next-generation alarms) and play music of the user's choice. Most modern televisions, computers, mobile phones and digital watches have alarm functions that automatically turn on or sound alerts at a specific time.