This is the 7437th most frequent Russian word.
грубо
Roughly; rudely.
Here, 'грубо' is used as an adverb describing the manner in which 'сказал' (said) was performed, expressing rudeness.
Он сказал это очень грубо.
He said it very rudely.
Here, 'грубое' is an adjective form describing the severity or harshness of the rule violation.
Это было грубое нарушение правил.
That was a gross violation of the rules.
In this example, 'грубо' is again an adverb modifying the verb 'разговаривай' (speak), indicating the undesirable rude manner of speaking.