Mi restas hejme pro la pluvo.

Restas is the present-tense form of the verb resti, meaning to stay, to remain, or sometimes to keep staying.

• resti = the basic dictionary form, to stay
• restas = stays / am staying / remain

So:

• Mi resti hejme = incorrect in a normal statement
• Mi restas hejme = I stay home / I am staying home

Esperanto uses -as for the present tense.

Here restas means stay rather than remain in the English sense of be left over.

So Mi restas hejme means:

• I am staying home
• I stay at home

Depending on context, resti can also mean remain, but in this sentence the natural idea is staying at home.

This is a very common question.

• hejmo = home as a noun
• hejme = at home / home as an adverb of place

In Esperanto, the ending -e often makes something adverbial. With place words, this often gives the meaning in/at that place.

So:

• hejmo = home
• hejme = at home

That is why Mi restas hejme means I stay home / I stay at home.

English can say home without at, but Esperanto usually uses the adverbial form hejme for that idea.

Yes, it is grammatically possible, but it sounds different.

• Mi restas hejme = I stay home / I stay at home
  This is the normal, natural way.
• Mi restas en la hejmo = I stay in the home/house
  This sounds more literal and physical, as if emphasizing being inside the building.

So in everyday speech, hejme is usually better when you mean simply at home.

Pro means because of, due to, or on account of.

In this sentence:

• pro la pluvo = because of the rain

It is followed by a noun phrase, not a full clause.

So:

• Mi restas hejme pro la pluvo = I stay home because of the rain

This is an important distinction.

• pro = because of
  • noun phrase
• ĉar = because
  • full clause

Examples:

• Mi restas hejme pro la pluvo.
  = I stay home because of the rain.

• Mi restas hejme, ĉar pluvas.
  = I stay home because it is raining.

Both are correct, but they are built differently.

La is the definite article, meaning the.

In this sentence, la pluvo usually refers to the specific rain that both speaker and listener understand from the situation, such as the current weather outside.

So:

• pluvo = rain, rainfall in a general sense
• la pluvo = the rain, this rain, the rain we are talking about

In context, pro la pluvo feels very natural: because of the rain.

Because it is the object of the preposition pro, not the direct object of the verb.

In Esperanto, nouns after prepositions normally do not take -n just because they follow a preposition.

So:

• pro la pluvo = correct
• pro la pluvon = incorrect in normal usage

The accusative -n is mainly for direct objects and for some expressions of direction or time, but not here.

Because hejme here means at home, not to home.

The -n can sometimes show direction with place expressions, but this sentence is about location, not movement.

Compare:

• Mi restas hejme. = I stay at home.
• Mi iras hejmen. = I go home.

So:

• hejme = at home
• hejmen = homeward, to home

Since resti does not express motion toward a place, hejme is correct.

No, Esperanto word order is fairly flexible.

The neutral order here is:

• Mi restas hejme pro la pluvo.

But you could also say:

• Pro la pluvo mi restas hejme.

This puts more emphasis on because of the rain.

Because Esperanto marks grammar through endings and prepositions, word order can move around more than in English, though some orders sound more natural than others.

Because Esperanto does not form the present progressive the way English does.

English often uses:

• I stay
• I am staying

Esperanto usually uses the simple present -as for both, depending on context:

• Mi restas = I stay / I am staying

So one Esperanto form can match more than one English form.

It can mean either, depending on context.

• If you are talking about what you are doing right now, it can mean I am staying home.
• If you are speaking more generally or habitually, it can mean I stay home.

In this sentence, with pro la pluvo, the most natural English meaning is often:

• I’m staying home because of the rain.

Not always. It can also mean remain.

For example:

• Mi restas hejme. = I stay at home.
• Nur unu pomo restas. = Only one apple remains.

So the exact English translation depends on context. In your sentence, stay is the right idea.