I have never been to Colombia, but I mentioned in another thread that when I tutored English I had some Colombian students whose English was almost unintelligible at times. They had a tendency to swallow consonants when speaking Spanish, and they carried that over to English.
Imagine hearing someone say SAW-tie. In the context of the sentence you may+ be able to determine that the person said +sometimes, but I would bet that you would not. I told the student that he had to sound both m's and the final s in order for native speakers of English to have a chance at understanding him.
You may hear "pa" for para, what sounds like "leeto" for listo. I don't think that the habit extends throughout Colombia, because I also had a few Colombian students whose Spanish and English were easier to understand. My guess is that anyone you encounter who is teaching the language will speak it clearly enough for you to learn it. In any case, you will become accustomed to the accent soon enough, whatever form it takes.
¡Suerte! Good luck!