The language of this condition is always weird… “On condition it is after 1 hour before sunset”
So, I think you meant to use an after with a negative offset, not a before:
alias: 'Licht aan bij thuiskomst Jos en donker '
description: ''
trigger:
- platform: device
device_id: 51c161782681b562ab5b521a547b747b
domain: device_tracker
entity_id: device_tracker.iphone_van_jc
type: enters
zone: zone.home
condition:
- condition: sun
after: sunset
after_offset: '-01:00:00'
action:
- service: light.turn_on
target:
entity_id: light.dimmable_light_1
mode: single
FYI: An after sunset condition will not work if you get home after midnight. If that is something that you need, you will need both a before and after:
condition:
- condition: or
conditions:
- condition: sun
after: sunset
after_offset: '-01:00:00'
- condition: sun
before: sunrise