The meaning of the 0 in this situation is that the 0 is there as a place holder. It is there to support the 1 so it has a bigger value instead of just 1.

<em><u>Solution:</u></em>
Given that,

We have to factor out terms and write as a product of 2 binomials and monomial
A monomial is a mathematical expression with only one term, while a binomial is a mathematical expression with two terms.
From given expression,

3 and a are common factors in second bracket

Hence, the product of two binomial is written in two binomial and a monomial