This is the 12686th most frequent Russian word.
короче
"Короче" means "in short" or "long story short."
Here, 'короче' is used as a discourse marker to introduce a summary or conclusion.
Короче, я передумал ехать.
In short, I changed my mind about going.
In this case, 'короче' is the comparative form of 'короткий' (short), describing a physical property.
Эта ручка короче той.
This pen is shorter than that one.
Here, 'короче' describes a manner of speaking, implying conciseness.