Monitor mode: Sniffing the packets in the air without connecting (associating) with any access point.
Think of it like listening to people's conversations while you walk down the street.
Promiscuous mode: Sniffing the packets after connecting to an access point. This is possible because the wireless-enabled devices send the data in the air but only "mark" them to be processed by the intended receiver. They cannot send the packets and make sure they only reach a specific device, unlike with switched LANs.
Think of it like joining a group of people in a conversation, but at the same time being able to hear when someone says "Hey, Mike, I have a new laptop". Even though you're not Mike, and that sentence was intended to be heard by Mike, but you're still able to hear it.
/dev/root on /rom type squashfs (ro,noatime)
devtmpfs on /dev type devtmpfs (rw,relatime,size=503920k,nr_inodes=125980,mode=755)
proc on /proc type proc (rw,nosuid,nodev,noexec,noatime)
sysfs on /sys type sysfs (rw,nosuid,nodev,noexec,noatime)
tmpfs on /tmp type tmpfs (rw,nosuid,nodev,noatime)
/dev/by-name/UDISK on /overlay type ubifs (rw,relatime,assert=read-only,ubi=0,vol=8)
overlayfs:/overlay on / type overlay (rw,noatime,lowerdir=/,upperdir=/overlay/upper,workdir=/overlay/work)
devpts on /dev/pts type devpts (rw,nosuid,noexec,relatime,mode=600,ptmxmode=000)
debugfs on /sys/kernel/debug type debugfs (rw,noatime)
none on /sys/kernel/config type configfs (rw,relatime)
adb on /dev/usb-ffs/adb type functionfs (rw,relatime)