Charlie is asking if it’s time to go for a walk. Which it is, and he’s happy!
But you might not know that by looking at him. He looks like he might be doing something big and noisy and scary.
When you meet a new dog always asks politely if he is friendly before you say hello. Everybody wants friends, but some dogs, like some people, feel shy or a little grumpy.
So ask: "May I pet your dog?" "Would you like to play with me?"
Most likely the answer will be yes, and you’ll have made a new friend! If the answer is no, say, "That's ok, maybe some other time."