Ok when the client A sends any packets to Client B following things will happen
1) Client A sends the packet to the Wireless Access Point to its antenna
2) The Access Point received the packet and then looks at its mac address table. If the destination mac address is directed toward it Ethernet interfaces then it will forward to that particular port.
3) If the destination mac address is in the radio interface then it’s transmitted as wireless signal.
Vice versa happens when the AP receives the packet for wireless station.