Can't tell you American British informal emphasis
Used to emphasize what you are saying
I can’t tell you how much I love you.
We can’t tell you how grateful we are for everything you’ve done for us.
I can’t tell you how gorgeous Maria is. She is too good to be true.
Used to describe the action of expressing one's opinions although others are dominating the conversation.
"Can" is used as a modal verb.
To be very wet
Because of forgetting bringing an umbrella, I look like a drowned rat when it rains.