Unknown icon next to clock on my iPhone's screen

You have Focus profile active.

Focus is ON. Swipe down the control centre and turn Off focus

See -> Turn on or schedule a Focus on iPhone

Turn on or schedule a Focus on iPhone - Apple Support (ZA)

Please provide a complete screenshot of the screen.

To improve understanding of the phenomenon, it would be highly beneficial if you could share a screenshot. Visual representations carry greater impact than written descriptions.

Please remember that this is a public forum, so when attaching a screenshot, please avoid including any personal credentials such as IP addresses, card details, email IDs, Apple IDs, IMEI numbers, serial numbers, phone numbers, order IDs, or any identifiable location information if you are sharing a map.

With the limited information that you have provided, It is hard to even guess the problems faced by you. 

You may get faster and better responses to your query by --> Writing an effective Apple Support Commun… - Apple ...

Please re-post with detail so that someone else can help.