The listing's default check-in and check-out times reflect the listing's time-zone.
The check-in and check-out times on the reservation page reflect your computer's time-zone.
For example, if a listing in Spain has a default check-in time of 4 PM, this will show up as 10 AM if you are viewing the reservation in New York.
You can change your computer's time-zone to match the listing's time-zone.