The phrase "I don't understand" expresses that you cannot grasp what was said or meant. It signals confusion about information, instructions, or reasons and invites clarification.
I'm supposed to have a Ph.D. on the subject of women. But the truth is I've flunked more often than not. I'm very fond of women; I admire them. But, like all men, I don't understand them. Frank Sinatra
I like women. I don't understand them, but I like them. Sean Connery
I don't understand how a woman can leave the house without fixing herself up a little - if only out of politeness. And then, you never know, maybe that's the day she has a date with destiny. And it's best to be as pretty as possible for destiny. Coco Chanel
I don't understand the word 'hunk.' Goran Visnjic
I don't understand how people can believe in God, even when I myself think of him everyday. Emil Cioran
The one thing I don't understand is war. Muhammad Ali