Learn Spanish (Latin America): Ella camina por el hotel como si fuera la reina. - She walks through the hotel as if she were the queen.

The phrase como si (as if) always requires the past subjunctive (also called the imperfect subjunctive). We use it because the comparison is hypothetical or unreal: she is acting like the queen right now, but she isn't actually the queen.

How do I form fuera from the verb ser?

Fuera is the imperfect subjunctive form of ser (to be). A great trick to find this form for any verb is to take the ellos/ellas form of the simple past tense (fueron), drop the -ron, and add the new ending. Here, fue- plus -ra gives you fuera.

Could I say como si fuese la reina instead?

Yes! In Spanish, the imperfect subjunctive has two interchangeable sets of endings: -ra and -se. Fuera and fuese mean the exact same thing, though the -ra forms are much more common in everyday Latin American Spanish.

Why does this sentence use por el hotel instead of para el hotel?

We use por to talk about movement through, along, or around a physical space. If you used para el hotel, it would indicate a final destination, meaning she is walking towards the hotel rather than around inside it.