Abe, Trump arrive at Japanese naval base

The video provides a brief introduction, expressing a positive sentiment.

What does the expression 'that's great' imply in a conversation?

In what contexts might someone say 'that's great'?

How can the phrase 'that's great' affect the tone of a discussion?

What are some alternative phrases to 'that's great'?

Can 'that's great' be used sarcastically? Provide examples.