Learn Spanish (Latin America): El pasillo está junto a la recepción.

Both mean almost exactly the same thing: next to or beside. Junto a can sometimes imply that two things are touching or directly adjoining, but you will hear native speakers use junto a and al lado de interchangeably for locations like this.

Why do we use está instead of es if the hallway is permanently there?

In Spanish, we always use the verb estar (like está here) to talk about where something is located physically. It does not matter if the location is permanent, like a hallway or a city, or temporary, like a person.

Does recepción just mean front desk?

It can mean the physical front desk of a hotel or office, the general lobby waiting area, or the action of receiving someone. In a building context like this sentence, it translates best as the front desk or reception area.

What else can pasillo mean besides hallway?

Besides a hallway in a building or house, pasillo is also the standard word for an aisle. You will use it when talking about the aisles in a supermarket, on an airplane, or in a theater.