A Wi-Fi deauthentication attack is a type of denial-of-service attack that targets communication between a user and a Wi-Fi wireless access point.
As you can see, this type of attack is pretty powerful and difficult to detect who is attacking. There are some tools for this attack like “aircrack-ng”(You can check the commands here).
So, basically the concept is the attacker broadcasts a wifi management “De-authentication” frame to victim’s to tell deauthenticate. It is like, “Hey client! can you please deauthenticate and authenticate”. Then the client will reconnect to AP(Access Point). These type of frames are supposed to send by valid “AP” to its clients, but the attacker can mimic these frames and broadcasts in the network.