that is to say; so that means; in other words
Colloquial phrase used to rephrase or draw a conclusion from what was just said. Equivalent to ということは in casual speech.
See also: ということは
I heard tomorrow is a day off. So that means we can relax until the day after tomorrow, right?
彼が来ないってことは、もう会えないのかな。
If he's not coming, does that mean we won't be able to see him anymore?