Apologies to Atilla and Chartsy, hopefully i didnt offend; i genuinely didnt mean to...
No not at all.
Dogs do understand when you talk to them. Not only that they sense your emotions. Psychiatrists and humans have to be tought to read body language but comes naturally to dogs who are very communicative.
They can sniff drugs, find dead bodies, guard areas and be tought to attack on command. They can also fetch the paper or slippers, sit, be quiete very easily with few words.
Some are even movie stars. 😉