Quick answer: Cuffing season is the stretch of colder months, roughly from fall through Valentine's Day, when a lot of single people feel a stronger pull to pair up. "Cuffed" is slang for being tied to one person, like a pair of handcuffs. The phrase caught on in the early 2010s. Some winter romances turn into something real. Others are mostly about company on cold nights. What matters most is knowing which one you want.
Quick answer: There's no one right answer for everyone. Getting back together can work when the reason you broke up has truly changed, you both want to try, and you feel calmer with this person, not more anxious. It's usually a no when you're mostly lonely, the same problems are still there, or you'd have to shrink yourself to make it work. Take your time. The choice is yours.