Que sí

Recall that say yes/no is translated with decir que. This can lead to a back-and-forth exchange:

— Quiero ir. I want to go.
— Ya te dije que no. I already told you no.
— Que sí. I'm going. I want to go.
— Que no. No, you're not going.
— Que sí. Yes, I am.
— Que no. No, you're not.

Think of que sí and que no as standing in for an entire clause. Here are examples with saber.

• Sí, ya lo sé que no. You're right. I know it's not fair.
• Pues yo sé que no. I know you can't.

How to repeat yourself in Spanish

Que is used to repeat something you said in the previous conversational turn.

The repetition can be due to the listener not hearing the speaker:

— Mañana viene. He's coming tomorrow.
— ¿Mande? Could you repeat that? I didn't hear you.
— Que viene mañana. I said he's coming tomorrow.

Or the repetition can be due to the listener not wanting to accept what the speaker said:

— Estás despedida. You're fired.
— ¿Qué? What?! I'm fired?
— Sí, que estás despedida. What you heard. You're fired. (telenovela dialogue)

Alternatively, the repetition can be due to a non-response on the part of the listener:

— Arranca. Start the car.
— (no response from the listener)
— Que arranques. I said to start it up. (movie dialogue)

Note from the previous example and the following one that a repeated command goes in the subjunctive.

— Espérame tantito. Hang on a sec. (said to someone on the phone)
— (inaudible: the person on the phone says something)
— Que me esperes. I said to hang on. (overheard at a quesadilla stand)

Listen for examples of this in the conversational speech you are exposed to.