Possible interpretations:
* "Grande o" could be a misspelling of "Grande, o" which would mean "Big, oh" in English. This is a common phrase used in some contexts to express surprise, disappointment, or disbelief.
* It could also be a partial phrase from a different language. For example, in Spanish, "grande" means "big" and "o" could be part of another word like "or," "of," etc.
To understand what "grande o" means, you need more context. Please provide more information about where you encountered this phrase.