We use there is and there are when we first refer to the existence or presence of someone or something:

There’s a letter on your desk. Julia brought it from the mail room.

Not: It’s a letter on your desk.

There are three Japanese students in my class.

There is and there’s are both singular forms. We use there’s more commonly in informal speaking:

There is a new cafe in the centre of town which sells Indonesian food.

She’s very determined and there’s no chance she will change her mind.

There are is the plural form of there is and there’s:

There are two new buildings next to the school. They are both science buildings.

In speaking and in some informal writing, we use there’s even when it refers to more than one. This use could be considered incorrect in formal writing or in an examination:

There’s three other people who are still to come.

There’s lots of cars in the car park.