Si lignum siccum est, securis id facilius findit.

Si means if and introduces a condition. In this sentence, Si lignum siccum est means If the wood is dry.

Latin uses si very much like English if.

Because siccum describes lignum, so the adjective has to agree with the noun in gender, number, and case.

• lignum = wood, neuter singular
• siccum = dry, also neuter singular

So lignum siccum means dry wood.

It is nominative singular.

That is because lignum siccum is the subject of est in the if-clause:

• lignum siccum est = the wood is dry

Even though English uses the same form for wood here, Latin shows its role by the ending.

Est is the 3rd person singular present of sum, meaning is.

It is singular because the subject, lignum, is singular:

• lignum ... est = the wood ... is

So the first clause literally says If the wood is dry.

Latin word order is more flexible than English word order. An adjective can come before or after the noun it modifies.

So both of these are possible in Latin:

• lignum siccum
• siccum lignum

The version in your sentence is perfectly normal. The placement does not change the basic meaning.

Securis means axe, and here it is the subject of findit.

So:

• securis ... findit = the axe ... splits

It is in the nominative singular, because it is the thing doing the action.

Id means it, and here it refers back to lignum.

Since lignum is neuter singular, the pronoun referring to it is also neuter singular:

• lignum → id

In the second clause:

• securis id facilius findit = the axe splits it more easily

Latin often uses a pronoun like this to make the object clear.

Id is accusative singular neuter here, because it is the direct object of findit.

It answers the question what does the axe split?

• The axe splits it
• therefore id is in the accusative

In neuter pronouns, the nominative and accusative singular often look the same, so the form id can serve as either depending on its role in the sentence. Here the role is object, so it is accusative.

Facilius means more easily.

It is a comparative adverb, formed from facile (easily). It modifies the verb findit.

So:

• findit = splits
• facilius findit = splits more easily

English expresses the same idea with more easily, not easilier.

Because it is describing how the axe splits, not describing a noun.

• An adjective describes a noun
• An adverb describes a verb, adjective, or another adverb

Here facilius tells us in what manner the splitting happens:

• the axe splits it more easily

So it modifies findit, the verb.

Findit is the 3rd person singular present active indicative of findo, findere, meaning to split, cleave, or rend.

So:

• securis id findit = the axe splits it

Because the subject is singular, the verb is singular too.

Latin often places the verb near or at the end of the clause, although word order is flexible.

So securis id facilius findit is a very natural Latin order:

• subject: securis
• object: id
• adverb: facilius
• verb: findit

English usually relies more heavily on word order, but Latin relies more on word endings.

Sometimes Latin can leave out an object if it is obvious from context, but here id makes the meaning clear and explicit.

With id, the sentence clearly says:

• the axe splits it more easily

Without id, the idea of what is being split would have to be inferred more strongly from context. So including id is very natural.

This is a general condition: it states something that is generally true.

• Si lignum siccum est = If wood is dry
• securis id facilius findit = an axe splits it more easily

Latin often uses the present indicative in both parts of a general, straightforward condition like this.

It can naturally be understood as if the wood is dry, but in context it can also express a more general truth, something like if wood is dry.

Latin has no article like English the or a, so whether you translate lignum as wood, the wood, or even a piece of wood depends on context.

Very literal:

• Si = if
• lignum = wood
• siccum = dry
• est = is
• securis = axe
• id = it
• facilius = more easily
• findit = splits

So, word for word, it is roughly:

If wood dry is, an axe it more easily splits.

That is not good English word order, but it shows how the Latin sentence is built.