There is nothing grammatically wrong with the word "are" here. The verb is plural because the subject, "words," is plural. "Words are [something]." The verb goes with the subject of the clause. "Beetles are a type of insect." The word "beetles" is plural, so the verb, "are," is plural. The fact that "a type of insect" is singular doesn't make the sentence incorrect. In fact, "type" has to be singular. If you say "beetles are TYPES of insects," then you are saying that beetles are MORE THAN ONE TYPE of insect. This is different from saying that beetles, as a whole group, are one type of insect. Frank P. is right that English speakers often make mistakes or use casual English that doesn't follow grammar rules. But this isn't an example of bad grammar. The word "are" is correct here.

Are you worried that "lie" is singular and "are" is plural. In English the the word before "to be" takes precedence over the word that follows. So "words" is plural so "are" is plural even though "a lie" is singular.

Your mistake is assuming most English speakers communicate in proper English. Pro tip- they don’t.:)

Thanks, bro <3. The problem is that many times we encounter many sentences in English which are 'grammatically ' wrong, but we assume that we are the ones making mistakes or in other words, 'it's our deficiency in English. But in reality, it is what you've just said "not all English speakers speak in terms of grammar or rules', anyway thank you.

Yes, of course it does. What it means is the eyes do not lie. Words do.