me: The accusative case of the personal pronoun, ego ("I"). The accusative case here is used to indicate who or what is the direct object of the verb. Personal pronouns are often found in second position (called "enclitic position": it is a complicated area of the Latin language that you might want to explore later when you can read better. You can find information on our Enklisis and Enlitics page.
Vocat: third person singular (he, she, it) present tense, indicative mood, active voice of the verb voco, vocare, vocavi, vocatus, "to call or summon" (cf. English "vocation"). The first word of the sentence give you the subject, labor, a masculine noun in the nominative singular. The verb must be in the singular number because this subject is a singular noun: this is called subject -verb agreement. To review the present active indicative, you may go to the Paradigm Page.
"Labor calls me" or
"My work summons me"
Labor in Latin is "hard labor, unrelenting work", more like the labor of childbirth. Personifications like this are not common in Latin, but they are common in begining Latin texts. The position of labor (first in the sentence) makes it emphatic: "It is labor that summons me."
Nihil: Nihil is an indeclinable neuter noun which means "nothing". The form nihil can be either the nominative or accusative case. Here we understand that it is the nominative subject because we already have an accusative direct object: me; therefore, nihil answers the question: What frightens me?
terret: 3rd person, singular, present tense, active voice, indicative mood
How do you know what the subject of the sentence is? In Real Latin this is rarely a problem because Latin has a rule: either you keep the same subject as you had in the last sentence, or you put the new subject in the first or second position in the sentence. Of course, like all rules of word order, this rule finds exceptions determined by context, rhetoric, desire for variety or for trickiness, and so on. But it is a good rule. Here, one might provisionally assume that the first word, nihil, which is an indeclinable neuter (that means, you only find it in the Nominative or the Accusative Neuter Singular; it has no other forms), is the subject. When you get to the verb, terret, you discover that it is in the third person singular: Therefore, nihil can fit as the subject and you are justified in taking it to replace the subject "he/she/it" which is implied by the verb ending. But you might notice that in the dictionary it says that nihil can also be an adverb and that it can mean "not." Actually, it is a very emphatic form of the negative adverb and means "not at all." Now, suppose you had been reading a letter from a friend who had been telling you about the English bully who just arrived at school: your friend just said, "He's always trying to pretend that he's better than everyone else. He pushes around the little guys and even tries to get in the face of the football players -- whom he says aren't real football players at all. But nihil me terret." Here, you would clearly assume that the subject of our sentence was the same as the subject of the previous sentences (that is, the English bully) and you would translate the same words, "he doesn't frighten me at all."
Nothing frightens me.
Nihil is a common term for "nothing", which like the English "nothing" is a compound of "ne-" = "no" + hilum = "a thing, a whit". It means "not a whit." terreo is more that "a fright", it is terror. There are several Latin terms for fear.