What does the word collo mean in Greek?

The word "collo" is not a Greek word. It is likely a misspelling or a part of a larger word.

Could you please provide more context or the full word you are referring to?

For example, if you are looking for the meaning of "colloquial," then the Greek word would be "δημοτικός" (dēmotikós), which means "popular" or "of the people."