Learn Spanish (Latin America): ¿Estás en el autobús ahora?

In Spanish, the preposition en can mean "in", "on", or "at". When talking about modes of transportation, you almost always use en, whether you are "in" a car (en el carro) or "on" a bus (en el autobús).

Why do we use estás here instead of eres?

We use the verb estar (to be) because we are asking about a physical location. You will use estar for locations and temporary states, while ser is used for more permanent characteristics. Since being on a bus is a temporary location, estás is the correct choice.

Where is the word for "you" in this sentence?

In Spanish, you can usually drop the subject pronoun (like tú for "you") because the verb ending already tells us who the subject is. The verb form estás specifically means "you are" (informal singular), so we don't need to actually say tú.

How do you form a question like this without changing the word order?

Unlike English, Spanish doesn't require a special word order to ask a question. You can turn the regular statement Estás en el autobús (You are on the bus) into a question simply by raising your voice pitch at the end when speaking, or by adding the inverted and standard question marks (¿ ?) when writing.