What does "lark" mean?

Is "comma" necessary here?

Yes, the comma is necessary here. Commas are needed to help mark a natural pause within the sentence when speaking. If you listen carefully to the video, you will hear that Blossom pauses after she says "Except for Buttercup." It's a very brief pause, but it is there. If the comma wasn't there, then Blossom would not have paused briefly in the sentence.

Is there any difference in meaning between "say about" and "talk about"?

Yes, there is a difference! "Say about" means that you're implying a certain quality or characteristic about something or someone, usually negative, sometimes positive. Whereas "talk about" means to chat about a topic or people in general, rather than a certain quality or characteristic. Ex: We were just talking about the camping trip. Ex: She had a lot to say about me to my friends after our fight. => negative qualities to share Ex: We didn't have much to talk about after our fight. => general chatting

How is it different between "exercise" and "practice"?

"Exercise" and "practice" are slightly different. In this context, they are used as nouns and both mean a small activity or task to test out a skill. As verbs, however, their use is different. "Practice" as a verb means to do something repetitively in order to get better at it, whereas "exercise" means to either engage in physical activity, or to utilize or apply something. Ex: Let's start class with a small math exercise. Ex: Our schools makes us exercise for 30 minutes in the afternoon. Ex: I have soccer practice five days a week. Ex: I want to improve my handwriting by practicing everyday.

Can I say "believe" instead of "understand" here?

No, I don't think you should use "believe" instead of "understand" here. "Believe" means to accept something as true but without certainty. "Understand" means to be aware of something. Victoria knows that her staff is not happy with her choices. If she used "believe" here, she wouldn't be sure about her staff's concerns. Ex: I believe this is the answer to your question. Ex: I understand that you want to transfer schools. Ex: She believes that aliens abducted her when she was a child. Ex: He understands the risks of joining the military.

What does "no-show" and "no-show protest" mean?

"No-show" means that nobody showed up for something. A "no-show protest" means that no one showed up for a protest. Ex: He was a no-show. Ex: The team won because the opponent was a no-show. Ex: I had an appointment with our internet provided, but he was a no-show. Ex: He had a blind date but she was a no-show.