What is tmp.0.sDQWBe? I have a file called tmp.0.sDQWBe located on my MacBook/Macintosh HD /private/var/folders/k1/(a ton of random text)/T/tmp.0.sDQWBe. The file is 13.2GB and I have no idea what it is.

I want to delete it so it can free up space on my computer. What is it, and can I delete it?
A simple reboot may purge some of this. /var is generally for variable files (caches, logs, etc). You can check to see which process is using the file before deleting, if it is indeed open. There are a number of ways to do this via the terminal. 

After a little research I found this gem of an article, What is "/var/folders"?.