The little clock icon on WhatsApp indicates that a message is still sending. When you send a message, it usually shows a single tick (✓) indicating that it has been sent, and when it is delivered to the recipient’s device, it changes to double ticks (✓✓).
However, if you see the clock icon, it means that the message hasn’t been sent yet, possibly due to a poor internet connection, either on your side or the recipient’s side. Once the message is successfully sent, the clock icon will disappear, and you should see the single tick. If there are persistent issues, you may want to check your internet connection or try resending the message later.