Chief
The leader all in white is the chief. All the other leaders are wearing some other color, but that's how you tell the chief apart from the other leaders.
Imagine all the leaders standing around, then the chief person standing there all in white.
はく, お
None
None
The reading is the same as 白, which is included in this kanji. The other reading is お, and it's like the honorific 御, in a way. You'd want to be polite to someone who is the chief ______, right? That's why it could be お, too.
You'll learn more about which reading to use when the vocabulary roll around. In the meantime, try to remember both of them the best you can!