A time zone is not a description of where the sun is. It is an agreement about what everyone will call the hour.
The clearest way to see the difference is to take two cities in the same zone — sometimes in the same country — and check what the sky is actually doing in each.
GHANA AND SENEGAL — both on UTC+0
The Prime Meridian runs through Tema, 25 kilometres east of Accra. Ghana keeps Greenwich Mean Time. So Accra's clock and Accra's sun reach midday within a couple of minutes of each other.
Dakar also keeps Greenwich Mean Time. But Dakar sits at 17.5° west — it is the westernmost point of the entire African continent. Its clock runs about 70 minutes ahead of its own sun.
Same zone. Same offset from UTC. An hour and ten minutes of difference in what that means.
SOUTH AFRICA — one country, one zone
South Africa runs entirely on UTC+2, calculated for the 30th meridian east.
Johannesburg sits at 28° east — about eight minutes off its own solar noon.
Cape Town sits at 18.4° east — about 46 minutes off.
One clock on the wall, thirty-eight minutes of disagreement about what it means, inside a single country.
CHINA — one country, five zones' worth of longitude
China abolished its five time zones in 1949 and put everything on Beijing Time, UTC+8.
Shanghai sits at 121.5° east, almost exactly on the meridian the zone is built around — the one major Chinese city where the clock is right.
Beijing itself is at 116° east: about sixteen minutes ahead of its sun.
Lhasa is at 91° east: about two hours.
Ürümqi is at 88° east: about two hours, and in practice the region runs a second, unofficial clock two hours behind Beijing to match the sky.
AUSTRALIA — where the sun and the state disagree seasonally
Adelaide and Darwin share UTC+9:30 for half the year. Then Adelaide moves to UTC+10:30 for summer and Darwin does not, because the Northern Territory has not observed daylight saving since 1944.
Two cities, one zone in winter, an hour apart in summer, without either of them moving relative to the sun.
And the extreme case.
Santiago sits at 70.6° west. On winter time, UTC−4, it is about 43 minutes ahead of its sun. On summer time, UTC−3, the zone reference jumps to the 45th meridian and Santiago finds itself more than 25 degrees west of it — roughly 103 minutes ahead.
The city's relationship with the sun changes by an hour, twice a year, without the city moving at all.
What this means for you.
Look up your own city's longitude, subtract the meridian your time zone is calculated from, and multiply the difference in degrees by four. That is how many minutes your clock is ahead of, or behind, the sun outside.
Almost nobody is at zero.