What is a thesis, I am not sure?

What is a thesis, I am not sure?
My teacher wants us to write an essay and she wants a thesis in the intro paragraph and I am not sure what a thesis is, can you help?

The intro paragraph should have three basic sentences. #1 is the attention getter, something clever to grab your reader’s attention. #2 is the topic sentence where, in general terms, you introduce the idea or topic of your paper. The thesis statement is #3. Here you tell specifically what you are going to write about your topic. You should have at least three specifics in your thesis statement.

Here’s a real quick example: #1 Of all the colors in the rainbow, what’s your favorite? #2 Crimson, not just plain old red, is mine. #3 I like crimson because I like red, because it reminds me of blood, and because it goes well with my other fav color orange.

Now you would develop your essay by writing a paragraph about why you like red; the next paragraph about why it reminds you of blood and the next paragraph describing how crimson goes so well with orange.

Concluding paragraph and you’re all set.

Good Luck