Use of Brackets
This question already has an answer here:
This is pretty simple actually. Inside a string context, like when wrapped in quotes, when you need to parse an object attribute like a method or property you wrap it inside curly braces.
 So this can help explain the statement: print "Author: {$product->getProduct()};  
Now second example is just an extension of the first one, where the author has used multiple lines and round brackets for readability. It can be also written as:
$b  = "{$this->title}"; 
$b .= "({$this->producerMainName},{$this->producerFirstName})";
$b .= ": page count - {$this->nPages}";
Here supposing we had following values:
$this->title = "Author Details ";
$this->producerMainName = "Doe";
$this->producerFirstName = "John";
$this->nPages = 10;
 Then if we had echoed $b after the assignments above we would get:  
 Author Details (Doe,John): page count - 10 
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