why a voice call symbol appears on whats app chat with duration

On WhatsApp, even in the Chat screen, you'll see calls that have been placed to or received from your interlocutor.

In your particular case, you placed 3 calls to that person and the time you see is actually the time at which the calls were placed. So you called at 12:37, 15:45 (3:45 PM) and 15:52 (3:52 PM.)

You will need to contact WhatsApp for help with their software, this is not an Apple product.

Here is a link to their help page.

https://www.whatsapp.com/contact/?subject=messenger