Curly braces has got 2 usage here:-
A. { .. } evaluates to an expression in JSX.
B. { key: value } implies a javascript object.
Let see a simple example.
<Image source={pic} style={{width: 193}}/>
If you observe pic is surrounded by single braces.
That's the JSX way of embedding variable. pic can be any Javascript expression/variable/object.
You can also do something like { 2+3 } and it will evaluate to { 5 }
Let's dissect style here. {width: 193} is a Javascript object.
And to embed this object in JSX you need curly braces, hence, { {width: 193} }
Note: To embed any kind of Javascript expression/variable/object in JSX you need curly braces.