Si nasus tuus frigidus est et bracchia quoque frigida sunt, domi manere melius est.

It is a conditional sentence:

• Si nasus tuus frigidus est et bracchia quoque frigida sunt = If your nose is cold and your arms are also cold
• domi manere melius est = it is better to stay at home

So the pattern is:

• si
  • condition
• main clause giving the result or advice

This is a straightforward, real condition, so Latin uses the indicative mood: est, sunt, est.

Si is the normal Latin word for if.

So:

• si nasus tuus frigidus est = if your nose is cold

It introduces the condition, just like English if.

Both are possible in Latin, because Latin word order is more flexible than English.

Here, nasus tuus is a natural way to say your nose. The possessive adjective tuus agrees with nasus and follows it.

Latin often places possessive adjectives after the noun, especially in simple statements, though tuus nasus could also occur for emphasis or style.

Tuus is a possessive adjective meaning your.

It agrees with the noun it describes in:

• gender
• number
• case

Here it goes with nasus, which is:

• masculine
• singular
• nominative

So the form is tuus.

Because adjectives in Latin must agree with the nouns they describe.

• nasus is masculine singular, so: frigidus est
• bracchia is neuter plural, so: frigida sunt

That is why the endings change:

• frigid-us
• frigid-a

And the verb changes too:

• singular noun → est
• plural noun → sunt

Bracchia is the plural of bracchium, meaning arm.

This is a neuter second-declension noun. In Latin, neuter nominative and accusative plural forms often end in -a.

So:

• singular: bracchium
• plural: bracchia

Even though -a may look singular to an English learner, here it is definitely plural. That is also why the verb is sunt, not est.

Quoque means also or too.

A very important point: quoque usually comes after the word it emphasizes.

So:

• bracchia quoque = your arms too / your arms also

This placement is very normal in Latin. English usually puts also before or too at the end, but Latin often puts quoque right after the emphasized word.

Latin often leaves out a repeated possessive adjective when it is already clear from context.

So although English might say:

• your nose and your arms

Latin can say:

• nasus tuus
• bracchia quoque

with your understood for the second noun as well.

If you wanted to be fully explicit, you could say bracchia tua quoque, but it is not necessary here.

Domi means at home.

It is a special form called the locative, used with a few words, especially names of places and certain common nouns like domus.

So:

• domi = at home

This is very idiomatic Latin.

You could sometimes see in domo, but that is more literally in the house/home. Domi is the standard compact way to say at home.

Manere is the present active infinitive of maneo, meaning to stay or to remain.

Here the infinitive works like a verbal noun in English:

• domi manere = to stay at home

Latin often uses an infinitive with expressions like melius est:

• domi manere melius est = it is better to stay at home

Literally, it is something like to stay at home is better.

Melius means better.

In this kind of expression, melius est means:

• it is better
• or literally is better

So:

• domi manere melius est = it is better to stay at home

This is a very common Latin way to give advice or make a judgment.

Latin does not need a dummy subject like English it in expressions such as:

• it is good
• it is necessary
• it is better

So Latin simply says:

• melius est

without adding a subject pronoun.

English requires it, but Latin does not.

Latin word order is flexible, and writers often arrange words for emphasis or style rather than following a fixed English-like order.

Here:

• domi manere puts the action first: to stay at home
• melius est gives the judgment: is better

So the sentence builds naturally toward the conclusion.

A very literal order would be:

• to stay at home is better

But in good English we usually say:

• it is better to stay at home

In normal prose, they are usually expressed, as they are here.

So:

• nasus tuus frigidus est
• bracchia quoque frigida sunt

are complete and standard.

Latin can sometimes omit forms of to be, especially in poetry or very compressed style, but a learner should treat the forms here as the normal way to say it.

Grammatically, yes: it gives a condition and then a recommendation.

It does not mean that staying home automatically happens; it means that staying home is the better choice.

So the sense is:

• If your nose is cold and your arms are cold too, it is better to stay at home.

That is why the second half is melius est rather than a future statement or command.