What does "sure" mean here?

Can I say "break legs" to express little more strongly for good luck?

No, you can't say that. It wouldn't be considered correct, and the meaning may not come across. But that would sound cool, honestly. If you wanted to express "good luck" strongly, you could add another encouraging phrase, such as "you've got this" or "you're gonna kill it." Ex: Break a leg. You've got this! Ex: You're gonna kill it. Now, go on and out and break a leg! Ex: This is the last performance of the week. Break a leg, everyone.

What does "successor" mean here?

"Successor" is a noun meaning a person or thing that succeeds another. You can think of it as being similar in meaning to "heir," "next-in-line," or "replacement." In this video, the speaker has used "successor" to refer to the next CEO of Adidas. Ex: I quit my job. My successor will take over starting next month. Ex: Have they chosen a successor for your position yet?

What does "calorie" mean?

"Calorie" is commonly known as the amount of energy food will produce if consumed. Some foods have a high or low "calorie intake." It's also common for people to watch or monitor their calories for fitness, health, or diet purposes. Ex: If you run a mile in 10 minutes, you'll probably burn 115 calories. Which is the same amount of calories that an apple has. Ex: As a general rule, people need to consume 1,200 calories every day to stay healthy. Ex: If you're doing strength training, I recommend increasing your calorie intake.

"I was like" is used a lot in this sentence, what's it mean? and when can I use it?

"I/he/she/they/you" + "was/were" + "like" is a very informal speaking pattern used to express that somebody said something. Here, "so he was like, 'no arm,'" means "he said, 'no arm'" in this context. It's a very American way of speaking that is now used by many English speakers when they want to quote or recount something that they or someone else said. Ex: And I was like, "you're kidding me!" Ex: I told the doctor my problem, and he was like, "you're not sick, don't worry!"

Why weren't the plural forms used here like "blow gales"?

There aren't any plurals in this sentence because the phrase "blow a gale" is an idiom. It is a weather-related idiom that means to be very windy. Idioms don't necessarily follow grammatical rules. This idiom is a British English idiom, but isn't commonly used in the United States. Ex: It's blowing a gale outside. Ex: Today is the perfect day to fly a kite! It's blowing a gale out there.