At the airport: Check in counter

💬 In Spain, [buenos días] is used well into the দুপুর-like middle of the day, often later than English [good morning].

💬 [A dónde] is the pattern for movement toward a place: [¿A dónde va?] = [Where are you going?]. For location instead, use [dónde]: [¿Dónde está la puerta?].

💬 [Viaja] here is the formal [you] form, the one staff use with passengers: [¿Viaja solo?]. With a friend it would be [viajas].

🇪🇸 At an airport counter in Spain, staff will normally speak to adult passengers with the formal form unless the situation becomes unusually casual.

💬 [Viaja] here is the formal [you] form, used for one person: [¿Viaja por trabajo?]. With [usted] verbs, the ending often looks like [he/she]: [viaja], [tiene], [necesita].

🇪🇸 This is standard polite counter language in Spain. You can answer in the same register, but you do not need to say [usted] yourself every time.

💬 Use [viajo a] before cities and many destinations: [Viajo a Madrid], [Viajo a Barcelona]. Before a country, it may change to [al] with masculine singular ones, like [Viajo al Japón] in theory, though with common country names you'll often just learn each one as you meet it.