In a wireless network, does wireshark sniffs all the packets that are in move, or only packets whom we are the destination/source ?
If the adapter is in monitor mode, it sniffs all packets that the radio receives. If it's not in monitor mode, it only seems packets sent to or from the machine. (Promiscuous mode may, or may not, work on Wi-Fi adapters.)
If it sniffs all the packets in the air, can someone explain
At the physical level, LAN adapters receive every packet on the wire to which they're attached, for wired LANs, and every packet on the channel to which they're tuned, for wireless LANs. The adapters normally look at the destination address and discard all packets not sent to one of the adapter's MAC unicast addresses, not sent to the broadcast address, and not sent to a multicast address to which the adapter is listening. In promiscuous or monitor mode, that check is turned off.