Learn Hardcore Esperanto: Kelkaj amikoj restos hejme sabate. - Some friends will stay at home on Saturday.

Kelkaj amikoj means some (unspecified) friends.
If you said la amikoj, it would mean the friends (some particular friends already known from context).
With words like kelkaj, multaj, miaj, tiuj, etc., you usually omit la, unless you want to emphasize very specific, known ones.

So kelkaj amikoj = some friends, without la.

What exactly does kelkaj mean? Is it some, a few, or several?

Kelkaj means an indefinite, smallish number of countable things. In English it usually corresponds to:

some friends
a few friends
several friends

Context decides which English word feels most natural, but in Esperanto kelkaj just says: more than one, but not many.

Why is amikoj plural? Could I say kelkaj amiko?

You must make the noun plural because kelkaj always refers to more than one:

amiko = a (single) friend
amikoj = friends

Since kelkaj means some / several / a few, the noun it modifies must take -j:

kelkaj amikoj ✅
kelkaj amiko ❌ (ungrammatical)

What tense is restos, and how is it different from restas and restis?

Esperanto verbs use fixed endings for tense:

restas – present: stay / are staying
restis – past: stayed / were staying
restos – future: will stay / are going to stay

In Kelkaj amikoj restos hejme sabate, restos says that the staying at home will happen in the future, on Saturday.

Why resti (to stay) and not esti (to be)? Could you say Kelkaj amikoj estos hejme sabate?

You could say Kelkaj amikoj estos hejme sabate, and it would mean Some friends will be at home on Saturday. But there is a nuance:

resti hejme = to stay at home, often implying:
- they are already at home and won’t go out, or
- they are choosing not to go somewhere else
esti hejme = to be at home, a neutral statement about location

So:

Kelkaj amikoj restos hejme sabate emphasizes the decision or fact of staying (not going out).
Kelkaj amikoj estos hejme sabate simply describes where they will be, with less focus on the idea of staying instead of going somewhere.

Why is it hejme and not hejmo or hejmen?

Esperanto often makes place adverbs by adding -e to a noun:

hejmo = home (the place, as a noun)
hejme = at home (location)
hejmen = (to) home, homeward (direction/movement)

In this sentence:

resti hejme = to stay at home (a state/location)
iri hejmen = to go home (movement toward home)

Because resti describes remaining in one place, you use the -e form: hejme.

Why is there no preposition before hejme? Why not ĉe hejmo or en la hejmo?

Hejme already includes the idea at home:

hejme literally functions like an adverb meaning at home.
Adding a preposition is usually unnecessary and would sound less natural.

You could say:

ĉe la hejmo or en la hejmo, but those sound more like:
- at the home / at the house (maybe a particular building, more physical)
- less like the everyday idiomatic at home

For stay at home, the standard, idiomatic expression is resti hejme.

What does sabate mean exactly? Why does it end in -e?

Sabate is a temporal adverb, built from:

sabato = Saturday (noun)
sabate = on Saturday / on Saturdays (adverb of time)

The -e ending turns it into an adverb, just like morgaŭ (tomorrow), hodiaŭ (today), tage (by day), etc.

So in the sentence, sabate answers when? → on Saturday.

Does sabate mean this Saturday specifically, or on Saturdays in general?

By itself, sabate can mean:

on Saturday (in a specific, understood context), or
on Saturdays (habitually)

Context decides which is meant. Some clarifications:

Ĉi sabate = this Saturday (coming Saturday)
Venontan sabaton = next Saturday (explicit future, with -n for time)
Sabate mi laboras = I work on Saturdays (habitually)

In Kelkaj amikoj restos hejme sabate, without extra context it is most naturally read as on Saturday (the one we’re talking about).

Could you say sabaton instead of sabate?

Yes, but there is a nuance:

sabate (adverb) – on Saturday in a general sense
sabaton (accusative of time) – for / during / on Saturday as a specific time point or span

Often they overlap in translation, but:

Kelkaj amikoj restos hejme sabate.
Neutral: Some friends will stay at home on Saturday.
Kelkaj amikoj restos hejme sabaton.
Slightly more like: They will stay home (for) the whole Saturday / for that Saturday.

In everyday speech, sabate is very common. Sabaton subtly emphasizes the time span more.

Can the word order change? For example, can I say Sabate kelkaj amikoj restos hejme?

Yes. Esperanto has fairly free word order, especially for adverbs of time like sabate. All of these are grammatically correct:

Kelkaj amikoj restos hejme sabate.
Sabate kelkaj amikoj restos hejme.
Kelkaj amikoj sabate restos hejme.
Kelkaj amikoj restos sabate hejme.

Differences are mainly in emphasis:

Sabate kelkaj amikoj restos hejme.
Puts a bit more focus on sabate (On Saturday is the frame of the sentence).

Learners are usually safe with the more neutral S–V–resting order:
Kelkaj amikoj restos hejme sabate.

Where would I put ne to make it negative, and does its position change the meaning?

The usual and neutral way is:

Kelkaj amikoj ne restos hejme sabate.
= Some friends will not stay at home on Saturday.

This means they will go out / be somewhere else.

If you move ne, you can change the meaning:

Ne kelkaj amikoj restos hejme sabate, sed ĉiuj.
= Not some friends will stay at home on Saturday, but all (of them).
Here ne negates kelkaj, not the verb.

So:

Kelkaj amikoj ne restos… → They won’t stay.
Ne kelkaj amikoj restos… → It’s not just some friends who will stay…

What is the difference between kelkaj amikoj and kelke da amikoj?

Both can be translated some friends, but their structure and nuance differ:

kelkaj amikoj
- kelkaj functions as an adjective/determiner.
- It agrees in number (and could in theory in case) with amikoj:
  - kelkaj amikoj, kelkajn amikojn, etc.
- Very common and straightforward.
kelke da amikoj
- kelke is an adverb-like quantity word, and da links it to the noun.
- Often used when focusing more on the amount than on the noun itself.
- Feels a bit more like a certain number of friends or some quantity of friends.

In practice, kelkaj amikoj is more usual in everyday speech for some friends.
Kelke da amikoj is grammatically fine but has a slightly more quantitative or formal feel.

Does kelkaj itself change form (like adding -j or -n), or does only the noun change?

Kelkaj behaves like an adjective, so it agrees with the noun:

kelkaj amikoj – some friends (subject)
mi renkontis kelkajn amikojn – I met some friends (object)

So:

Singular: kelka amiko (rare, usually you don’t say this)
Plural: kelkaj amikoj
Accusative plural: kelkajn amikojn

Both kelkaj and amikoj take -n in the accusative, because they form one phrase.

Could I say Kelkaj el miaj amikoj restos hejme sabate? What is the difference from the original?

Yes, that is correct Esperanto, and it is a bit more specific:

Kelkaj amikoj restos hejme sabate.
= Some friends will stay at home on Saturday.
(No information about whose friends they are.)
Kelkaj el miaj amikoj restos hejme sabate.
= Some of my friends will stay at home on Saturday.
(Clearly says that the group is my friends, and only some of them will stay home.)

Kelkaj el X = some of X, indicating a subset of a specific group.