Yes, Ella and Effie understand EVERYTHING I say, they choose to ignore most of it!
There are things they do understand - through reptition I think.
If there is a fly in my house - and god created flies just for my cats to do mad for - I say "where is it" and they freak out. So much so that whenever I say those words, they go into a chattering frenzy looking at the ceiling. The other day I was looking for something and couldn't find it and shouted "Where is it". Both girls came running thinking it was a fly!
They know their names and will come if called, no mater what tone I used and Ella comes when I call Ella and Effie comes when I call Effie, so I know they know their individual names.
All Ella likes to play "stick game" where she fetch's and returns a stick I throw. if I saw "Stick game" She bounds off and comes back to me with the stick in her mouth ready to play.