This is the 1st most frequent Greek word.
και
"And."
The word "και" is used as a coordinating conjunction meaning "and," connecting Nikos and Maria as subjects of the sentence.
Ο Νίκος και η Μαρία πήγαν σινεμά.
Nikos and Maria went to the cinema.
Here, "και" is used again as a conjunction meaning "and," connecting the actions of raining and blowing.
Βρέχει και φυσάει πολύ σήμερα.
It is raining and blowing hard today.
In this sentence, "και" acts as an adverb meaning "also" or "even," emphasizing the liking of chocolate within the context of sweets.