Why is my Airpod not connecting even if it is charging

My problem is with my left Airpod, it charges fine( I think) because when I removed both AirPods, then just put the left one in, the charging indicator flashed. But, when I put it in my ear it does not sound the connection ring. Also, if I have the right Airpod in, on my phone it shows that it is charging, but when only the left is in, nothing is shown as charging.

the right Airpod works perfectly fine.