There is/are (something)(somewhere)

It's common to use "there is ___" or "there are ___" when you're describing a scene or situation:

When you go in his office, there are books scattered all around.

You could also describe a scene this way:

When you go in his office, books are scattered all around.

But that's not as common, because it doesn't communicate the sense that you're giving a description. It sounds more like you're stating a fact. "Facts" are pieces of information like this:

Math textbooks cost a lot of money.

But a "description" has a slightly different feeling. It kind of invites the listener to imagine that they are in the situation you're describing:

There was a math textbook at the campus bookstore that cost a hundred and ninety dollars!

So when you're describing a scene, it's more common to use "There is", "There are", "There were", etc.:

There were books scattered all over.

you know?

Some English speakers, especially younger ones, use "you know?" on the end of their sentences. There's not a lot of meaning to it, but people use it when they want the listener to agree with the feeling or emotion of what they're saying. For example:

I kind of feel obligated to go, you know?

In this example, someone doesn't want to go to a party, but she feels like she has to. She wants the listener to agree with that feeling, so she says "you know?" at the end of the sentence. Another example:

You can't beat face-to-face communication, you know?

There are some people who over-use "you know" and put it in almost half of their sentences. It doesn't sound very intelligent when you do this.

When someone who's speaking to you says "you know?", it's good to nod your head or say something like "Yeah."

click with (someone)

To “click with” another person is to have a strong, effortless personal connection with them. If you meet someone and talk for an hour without any awkwardness, you probably 'click' well with this person. For a romantic relationship, this “click” is especially important:

I didn’t really click with anyone I met on any of those online dating sites.

We probably wouldn’t use this term in formal or business writing, but it’s quite common in speech and casual written communication.

(something happens) immediately

"Immediately" can mean right after meeting someone, right after seeing something, etc.:

The very first time I met her, I knew immediately that she was the woman I wanted to marry.

When I saw him in that costume, I immediately started laughing.