5. Errare est humanum
errare: The inifinitive is an abstract indeclinable neuter verbal noun. This Present Infinitive Active serves as the subject of est.
humanum: this is a predicate adjective, defining or describing the subject, errare. Since errare is a neuter singular noun, the predicate adjective must be a neuter, nominative, singular adjective.
To err is human.
errare: literally, the term means "to wander". The English term "error" comes from this word.
11. Da mihi multa basia, mea bella puella!
Mihi is the dative of the first person pronoun. Datives usually designate the person for whose benefit/profit or detriment/harm the action of the verb happens; this is called in English the "indirect object." Because this function is found so often with and almost required by the verb "to give", it has received the name dative ("related to giving" do, dare, dedi, datum). This connection, however, distorts the basic meaning of the Dative Case: it does not usually mean "to someone", but "for someone."
mea bella puella: feminine, singular, vocative
Mea and bella are both adjectives that are modifying the noun puella. Remember that adjectives must agree with the nouns they modify in three ways: case, number and gender!
Puella is vocative as it is the addressee of the command "Da". Someone (here the poet Catullus) is directly speaking to the girl; therefore, puella is in the vocative case which is used in direct speech.
Give me many kisses, my beautiful girl!
This sentence is a revised version of a famous line from the Roman poet, Catullus. The polite term for kisses in Latin is osculum (literally, "a little mouth"); basia is the real mouthful.
14. Mali sunt in nostro numero et de exitio bonorum virorum cogitant. Bonos adiuvate; conservate
Mali: Masculine, plural, nominative adjective. Here mali is being used as a substantive adjective; therefore it is the subject of the sentence.
nostro: masculine, singular, ablative, adjective modifying numero (also ablative, singular, masculine). Remember that adjectives always agree with the nouns they modify in case, number and gender.
Bonos, the adjective, is used substantively. Since it is masculine you ought to supply something like "men" or whatever masculine that fits the context. Sometimes, however, it makes more sense to just put in "people" and leave it at that.
adiuvate: second person, plural, imperative
conservate: second person, plural imperative
The imperative mood is used in Latin to give commands. The person will always be second but the number can be either singular or pluarl depending on whether you are commanding one person (sing.) or more than one person (plu.).
There are evil men in our number (among us) and they are thinking about the destruction of good men. Help the good men; save the Roman people.
This rewrites a sentence in Cicero's speech to the Senate against Catiline. It is unfortunate that in rewriting Cicero the text has made an error: adiuvate is an imperative and in Latin as in English you place an imperative first in a sentence: it is preemptive. More idiomatic Latin would be: adiuvate bonos…