A large collection of word lists can be found here.
rockyou.txt is a leaked unencrypted password list from RockYou. On Kali, it can be found under /usr/share/wordlists/rockyou.txt.gz. Use gzip -d rockyou.txt.gz to unzip it.
rockyou.txt
/usr/share/wordlists/rockyou.txt.gz
gzip -d rockyou.txt.gz