It’s just an artificial shift. There’s still the same amount of hours in the day.
If they didn’t change it, in the middle of the summer the sun would rise at about 4 am and set about 8 pm (+/- 8 hours from midday). Since there’s a lot more people up and about at 8 pm than 4 am, we arbitrarily move everything “ahead” 1 hour in the summer, so sunrise is 5 am and sunset 9 pm.
Double-daylight savings time has been tried too, but it near-impossible to get kids to sleep when it’s still light out at 11 pm!