What does "reckon" mean?

Why is the verb "are" used here? I thought it should be "is" because the singular noun "person" is used.

You are right that the singular noun "person" is used here, however, the plural noun "crewmates" is also used here. So since they refer to the plural of "one or two crewmates" in this sentence, the verb "are" is used.

I saw people say "what?" "pardon?" "excuse me?" besides "sorry?" when they couldn't understand what the other said. But I don't know the difference between them. Is there a difference in nuance?

The difference comes in politeness and tone! "What?" is considered the most casual or rudest of them all. It isn't very polite to say this to a stranger. "Excuse me?" is often said with another phrase to sound more polite. "Pardon?" is the most polite and formal of them all. But it can also be used in casual contexts. "Sorry?" is quite neutral depending on your tone. Or it can indicate hesitancy as it does here! Ex: What? You're not making any sense. Ex: Excuse me, can you say that again? Ex: Pardon? I didn't quite catch that last part. Ex: Sorry? What do you mean?

In the world of politics, what's the main difference between "administration" and "cabinet"?

A "political administration" is the group around the official person that's in charge. These individuals help the president manage different tasks. In American politics, this consists of the president, vice president, first lady or gentleman (president's spouse), second lady or gentleman (VP's spouse), the president's executive office, and the cabinet. A "cabinet" is a group of individuals who advise the president on different decisions. In American politics, this includes the vice president, Secretary of State, Secretary of Defense, Secretary of Treasury, etc. Ex: The United States is currently under the Biden Administration. Ex: Lloyd Austin is a member of the cabinet.

What does "your kind" mean here?

"Your kind" is a derogatory statement that means "Your race or your ethnicity." Saying "your kind" to someone else means that you are objectifying that person due to his or her race. I recommend that you never say this to someone else. This is a very offensive and racist comment that could get you into a lot of trouble and will also make you hated by others. In this show, everyone calls Geralt "your kind" because his race is "Witcher." Most people are afraid of Witchers and don't want anything to do with them.

What does “back talk” mean?

If someone gives a "backtalk", it means that the person is replying to you in a rude and disrespectful way. "Backchat" is the synonym for "Backtalk". Here are some examples of backtalk: Ex: Mom will get angry if you give one more backtalk. Go to bed right now. Ex: Backtalk is not a good way to deal with fights in a relationship.