Hi, this is a simple question but bear with me

What does the France UA mean??
"Museum and World Wonder theming bonuses are doubled in their capital".
A museum gives +5 Culture, so it means I guess that this bonus in doubled to +10
...but what is a theming bonus and which Wonders are in applied to?
You do not get double base ulture from France's UA.
An example;
The museum has 2 great works slots that can be filled with great works of art or artifacts.
The museum produces 1 culture on its own.
If you put a great work of art or an artifact in a museum, it gains 2 culture and 2 tourism, for a total of 3 culture and 2 tourism. France will receive 3 culture and 2 tourism (the same as any other civ).
The theming bonus for the museum is to place 2 great works of art, or 2 artifacts from the same era and same civilization. You will receive +2 culture and +2 tourism for the theming bonus.
A themed museum gets 7 culture and 6 tourism for a standard civ. for the culture, it 1 from the building, 2 from each artifact, 2 from the theme. For the culture, it is 2 from each artifact, and 2 from theme.
France gets 9 culture and 8 tourism from a themed museum. You get the same base as above, but you get 4 culture and 4 tourism from the theming bonus.
So the important thing to keep in mind is that you get double
theming bonus, not double base.
If you take full aesthetics, France will get 13 culture and 12 tourism before modifiers from a museum.