(someone) is in charge of (something)

There are two ways that we use "in charge of ___". First, you can be "in charge of" a specific job or duty:

Eric, you're in charge of the food. Takeru is in charge of booking the DJ and so on.

Or you can be "in charge of" a person or a group of people:

When you're in charge of a team of over 30 people, it's pretty stressful.

In both cases, being "in charge" means that you are the leader or the person who's responsible.

the East Coast

In the United States, the states that touch the Atlantic Ocean on the eastern side of the country are called the East Coast. There are about 14 states on the East Coast. People contrast the East Coast with other parts of the country, like the West Coast or the Midwest.

A: Did you grow up here?

B: No, I'm from the East Coast.

Other countries can also have an east coast, if there's an ocean or sea on the eastern side. In some places like the U.S. and Australia, "East Coast" is capitalized. In other places, it isn't.

a sales team

A group of salespeople is often called a "sales team".

There are rumors that they're planning to lay off their entire sales team.

A "team" can mean all of the salespeople in a company, or it can mean a specific group of salespeople. For example, a company might have different sales teams for different regions.