Learn Spanish (Latin America): Según el rumor, van a contratar a una chica para el puesto. - According to the rumor, they are going to hire a girl for the position.

Exactly! Even though there isn't a verb like dice (says), según (according to) is a very common way to report what you've heard. You can use it with a noun, like según el rumor (according to the rumor), or a person, like según Juan (according to Juan).

Who is the 'they' in van a contratar?

Just like in English, this is the 'impersonal they.' The speaker doesn't know (or doesn't need to say) exactly who is doing the hiring—it just refers generally to the managers or the company.

Why is there an a before una chica?

This is the 'personal a.' In Spanish, when the direct object of a verb is a person, you must put an a right before it. Here, the girl is the person being hired, so it becomes contratar a una chica.

Why do we use para instead of por here?

We use para because it shows the destination or purpose of the action. The girl is being hired for a specific destination: the job role. Note that puesto in this context means 'position' or 'job role,' not the past tense of 'put'!