The Apple includes them to give an indication of what the Watch is or isn't doing, a mode that it is in, apps that are active, and communication and app notifications. Most of the symbols are intuitive enough to be worked out — or at least to only need explaining once — but there'll likely be at least one that a won't know.
When the Apple Watch was first launched in 2015, many aspects of it were familiar to people who had used other mobile devices. It needed charging and had connectivity features, for example, both of which s would know from elsewhere and therefore had icons that most would recognize. Other features were new or unique to the Apple Watch, though, and so there was a learning curve for these that included the symbols to represent them.
Among the most identifiable Apple Watch symbols are a red lightning strike to indicate a low battery and a green lightning strike to indicate that the Watch is charging. Similarly, an airplane symbol, recognizable from most smartphones, shows that Airplane Mode — which turns off wireless functionalities — is enabled, a crescent moon shows that Do Not Disturb mode is on, a padlock indicates that the Watch is locked, and there's the ubiquitous Wi-Fi symbol. In the Control Center, there's a recognizable symbol for GPS connectivity, although only a number of dots are shown at the top of the display to indicate signal strength.
Lesser-Known Apple Watch Symbols
One symbol that is recognizable but that some s may not know what it does is that of the two theater masks, which indicate that Theater Mode is enabled. Theater Mode darkens the screen and puts the Apple Watch into Silent Mode too for occasions like performances when the and others should not be interrupted or distracted. A crossed-through iPhone symbol means that a connection between the two devices has been lost, while a red X indicates that a GPS cellular connection has dropped out.
A single s can track their sleep patterns.
Finally, there are a number of icons to show that apps are currently active. A person running shows that a workout is in progress, a walkie-talkie shows that the Walkie-Talkie app for chatting to friends is active, and an arrow curving to the right appears when s are navigating with a third-party app. A Now Playing icon of vertical lines getting longer to the left appears when audio is playing and a microphone symbol appears when the Apple Watch mic is listening.
Source: Apple