Hello , i have this excercise i have to learn for my exam tomorrow! I just have to do with a random word these things (eg. windows)

w w swodniw wInDoWs , I've been searching a lot but couldn't find
wi i it anywhere
win n If you can help me , please do it :)
wind d..
windo
window
windows

Can you explain the excercise and what you don't understand a bit ?