Let's break it down:
* vimarshnapoorvam: This is an adverb meaning "thoughtfully" or "with consideration." It is formed by adding the suffix "-poorvam" to the word "vimarshna," which means "consideration" or "thought."
* vilayiruthuvan: This is a verb meaning "he is playing." It is formed by combining the verb "vilayu" (to play) with the third-person singular masculine present tense ending "-van."
So, the sentence essentially conveys that someone is engaged in play, but doing so in a careful and thoughtful manner.