Mi aĉetas novajn ŝtrumpojn kaj botojn por la venonta vojaĝo.

Because they are plural direct objects.

In Esperanto:

• -o = noun
• -j = plural
• -n = accusative, usually marking the direct object

So:

• ŝtrumpo = a sock/stocking
• ŝtrumpoj = socks
• ŝtrumpojn = socks, as a direct object

And:

• boto = a boot
• botoj = boots
• botojn = boots, as a direct object

Since both are things being bought, both take -n.

Because adjectives in Esperanto agree with the nouns they describe.

Here is the pattern:

• nova = new
• novaj = new, plural
• novan = new, accusative singular
• novajn = new, accusative plural

Since ŝtrumpojn is plural and accusative, the adjective must match it:

• novajn ŝtrumpojn = new socks

This agreement is one of the most regular parts of Esperanto grammar.

Grammatically, novajn is directly attached to ŝtrumpojn, so the most literal reading is:

• new socks and boots

In context, some people may understand that both items are new, but if you want to make that completely clear, it is better to repeat the adjective:

• Mi aĉetas novajn ŝtrumpojn kaj novajn botojn.

So in the original sentence, only the socks are explicitly marked as new.

It can mean either, depending on context.

The ending -as marks the present tense in Esperanto. That tense often covers both:

• I buy
• I am buying

So:

• Mi aĉetas can mean I buy or I am buying

Esperanto usually does not force the same distinction that English does between simple present and present progressive.

Esperanto has only one article: la, which means the.

There is no separate word for a or an.

So:

• la venonta vojaĝo = the upcoming trip
• novajn ŝtrumpojn kaj botojn = new socks and boots / some new socks and boots

The article appears before venonta vojaĝo because this is understood as a specific trip: the upcoming trip. The socks and boots are not presented as specific known items, so no article is used.

Venonta means coming or upcoming.

It comes from the verb veni = to come, plus the participle element -ont-, which refers to something about to happen or future.

So:

• veni = to come
• venonta = coming, upcoming

Therefore:

• la venonta vojaĝo = the coming/upcoming trip

This is a very common Esperanto way to express upcoming.

Por means for, in the sense of intended for or for the purpose of.

So:

• por la venonta vojaĝo = for the upcoming trip

This tells you why the speaker is buying the socks and boots.

A useful comparison:

• por = for
• pro = because of

So here por is correct, because the trip is the purpose or intended use.

The word order is fairly flexible.

The basic order here is:

• Mi = subject
• aĉetas = verb
• novajn ŝtrumpojn kaj botojn = object
• por la venonta vojaĝo = purpose phrase

But you could also say:

• Por la venonta vojaĝo mi aĉetas novajn ŝtrumpojn kaj botojn.

That shifts emphasis slightly to the trip. Because Esperanto marks grammar clearly with endings, word order can often be moved around more freely than in English.

The special letters here are:

• ĉ in aĉetas: like ch in church
• ŝ in ŝtrumpojn: like sh in shoe
• ĝ in vojaĝo: like the s in measure or the g in genre

A few other useful pronunciation points:

• j usually sounds like English y
• oj sounds roughly like oy in boy

So:

• aĉetas sounds roughly like ah-CHEH-tas
• ŝtrumpojn sounds roughly like SHTROOM-poyn
• vojaĝo sounds roughly like voy-AH-zho

Esperanto pronunciation is very regular, so once you learn the letters, they stay consistent.

It breaks down like this:

• Mi = subject, I
• aĉetas = verb, buy / am buying
• novajn ŝtrumpojn kaj botojn = direct object, new socks and boots
• por la venonta vojaĝo = prepositional phrase, for the upcoming trip

So the structure is basically:

• Subject + verb + object + purpose phrase

That is a very common and straightforward Esperanto sentence pattern.