putty

hi i got this message a couple of times and ignored it for a couple times but then when I was reading what was wrong I followed the instructions the pi gave me and I followed these steps : journalctl -xb then this systemctl reboot to reboot it and then type systemctl default or ^d and I rebooted twi...

You type in the terminal "df" and it shows a bunch a numbers and we cannot understand you need to type "df -h" and gives it in gb