Si ullus amicus apud nos manet, ei semper lectus paratus est, et intra domum tutus erit.

Not necessarily. Latin uses the indicative in ordinary, straightforward conditions.

So si ullus amicus apud nos manet means something like if any friend stays with us or if any friend is staying with us. It presents the condition as a real possibility, not as hypothetical, contrary to fact, or doubtful in a special way.

The subjunctive would suggest a different kind of condition or nuance. Here, the indicative is the normal choice.

Ullus means any or any at all.

In English, any is very common after words like if, not, and in questions. Latin often does something similar: words like ullus are especially natural in conditional contexts.

So:

• ullus amicus = any friend
• with a slight force of any at all

It helps make the sentence general: this is not about one specific friend, but about any friend who may stay with us.

Amicus is nominative singular masculine.

You can tell because it is the subject of manet:

• amicus manet = a friend stays

Also, ullus agrees with it:

• ullus amicus = any friend

Both are masculine singular nominative.

Apud nos is a very natural Latin way to say at our house, among us, or with us in the sense of staying at our place.

A learner might expect cum nobis, but that would usually mean with us in the sense of in our company, not specifically at our home.

So:

• apud nos manet = he stays with us / at our place

Also note that apud takes the accusative, so nos here is accusative.

Manet comes from maneo, which often means:

• remain
• stay
• continue
• sometimes wait for

Here the meaning is clearly stays or is staying.

So amicus apud nos manet means a friend stays with us or is staying at our place.

Ei is dative singular, meaning to him or for him.

It refers back to amicus. In this sentence:

• ei semper lectus paratus est

the idea is a bed is always ready for him.

The dative is used because Latin often uses the dative for the person something is prepared, suitable, useful, available, and so on.

So the structure is:

• lectus = the bed
• paratus est = is ready
• ei = for him

Because sibi is a reflexive pronoun, and reflexives normally refer back to the subject of their own clause.

In ei semper lectus paratus est, the grammatical subject of that clause is lectus, not amicus.

So sibi would be awkward or misleading here. Ei is the normal non-reflexive form meaning for him.

Yes, here lectus is the noun bed.

That is clear from the context and from the sentence structure:

• lectus paratus est = the bed is ready / a bed is ready

There is also a form lectus connected with the verb lego (chosen, read, depending on context), so a learner may hesitate. But here the meaning bed is the only one that makes sense.

Also, this lectus is a common noun meaning bed or couch.

In this sentence, the best sense is is ready.

Literally, paratus is a participle meaning prepared, so lectus paratus est can sound like the bed has been prepared. But very often in Latin, this kind of participle + est works like an adjective describing a state:

• paratus est = is ready

So here the meaning is not mainly about the action of preparing the bed, but about the result: the bed is available and ready.

Latin has no articles like English a, an, or the.

So:

• amicus can mean a friend or the friend
• lectus can mean a bed or the bed
• domum can mean a house/home or the house/home

You decide from context. In this sentence, English naturally uses any friend, a bed, and the house or the home, but Latin does not need separate words for those.

Because intra is a preposition that takes the accusative.

So:

• intra domum = inside the house

This is just the normal construction.

A learner may expect in domo, and that would also be possible in many contexts for in the house. But intra gives a stronger sense of inside, within the limits of.

So the difference is roughly:

• in domo = in the house
• intra domum = inside the house / within the house

That change of tense reflects the sense nicely.

The first part describes a general standing situation:

• If any friend stays with us
• a bed is always ready for him

Then the sentence gives a result or promise:

• and he will be safe inside the house

So erit looks forward: once that friend is staying with us, he will be safe.

Latin can shift like this when the meaning moves from a general present situation to a future consequence.

Because it agrees with the person being described: the implied he, referring back to amicus.

So:

• amicus = masculine singular
• tutus = masculine singular

If the subject were feminine, you would expect tuta instead.

Latin adjectives have to agree with the noun or pronoun they describe in gender, number, and case.

The subject is understood from the context: it is the same friend already mentioned earlier.

So:

• tutus erit = he will be safe

Latin often leaves out a subject pronoun when it is clear from context. English usually has to say he, but Latin does not need to.

Because Latin word order is much more flexible than English word order.

English depends heavily on position:

• the friend sees the dog
• the dog sees the friend

Latin depends much more on case endings, so it can move words around more freely without changing the basic meaning.

Here:

• ei semper lectus paratus est

could be rearranged in other ways and still mean basically the same thing, because:

• ei is dative
• lectus is nominative
• paratus agrees with lectus

The chosen order helps the sentence flow naturally, but the endings carry the grammar.