Learn Hardcore Indonesian: Sepatu bot itu dipakai juga ketika hujan deras di lapangan. - Those boots are also worn when it rains heavily on the field.

sepatu bot itu ≈ those boots / the boots
It tells us the listener already knows which boots are being talked about (mentioned earlier or clear from context).
Indonesian doesn’t mark plural on the noun, so sepatu bot itu can be that boot or those boots depending on context. The form itself doesn’t change.

You could drop itu and just say sepatu bot if you want to speak more generally about boots, rather than specific ones.

Why is dipakai (passive) used instead of an active form like memakai?

Dipakai is the passive form of memakai (to wear / to use).

memakai sepatu bot itu = (someone) wears those boots
sepatu bot itu dipakai = those boots are worn

Indonesian often uses the passive when:

The doer (subject) is not important, obvious, or general (like “people”, “we”, “players”).
You want to focus on the object (the boots), not on who is wearing them.

So Sepatu bot itu dipakai... is very natural and matches the English passive Those boots are worn... without needing to say by us / by them unless you really want to specify:

Sepatu bot itu dipakai oleh para pemain. = Those boots are worn by the players.

Can I also say Sepatu bot itu juga dipakai...? What’s the difference in meaning with dipakai juga?

Both are correct, but the nuance and rhythm are slightly different:

Sepatu bot itu juga dipakai ketika hujan deras di lapangan.
- Very natural and common.
- juga is attached closely to the verb phrase dipakai.
- Feels like a straightforward “Those boots are also worn when...”.
Sepatu bot itu dipakai juga ketika hujan deras di lapangan.
- Also possible.
- Placing juga after dipakai can sound more like you’re adding “as well” / “too” at the end of that part, sometimes with a bit of extra emphasis, depending on intonation.

In everyday speech, Sepatu bot itu juga dipakai... is slightly more typical, but both forms are acceptable and understood the same in most contexts.

What’s the difference between ketika, saat, and waktu? Could I replace ketika here?

All three can mean when, but there are nuances:

ketika
- Neutral, common in both spoken and written Indonesian.
- Works for both long and short events.
saat
- Very common too; sometimes feels a bit more like “at the moment when / at the time when”.
- Often used in slightly more formal or written contexts, but also everyday speech.
waktu
- Literally time, but in many contexts it’s used like “when”.
- Can sound a bit more conversational depending on the sentence.

In your sentence, you can say:

...ketika hujan deras di lapangan.
...saat hujan deras di lapangan.
...waktu hujan deras di lapangan.

All are grammatical and natural; the meaning is essentially the same here.

Why is it hujan deras and not deras hujan?

In Indonesian, adjectives normally come after the noun:

rumah besar = big house
baju merah = red shirt
hujan deras = heavy rain

So hujan (rain) is a noun, deras (heavy, intense) is an adjective describing the rain.

deras hujan is not the standard noun–adjective order; it would sound wrong as a noun phrase. You can use deras in other structures (like hujannya sangat deras = the rain is very heavy), but as a direct phrase, it should be hujan deras.

What exactly does di lapangan mean? What kind of “field” is lapangan?

Lapangan is a general word for an open area, often flat and used for activities. Depending on context, it can mean:

a sports field (soccer field, etc.)
a yard / open ground
a square / open space (e.g. lapangan kota = town square)
“in the field” (as opposed to in the office) in some work contexts

In this sentence, di lapangan most likely refers to a sports or outdoor field where you might be wearing boots in the rain.
If you wanted to be very specific, you could say di lapangan sepak bola (on the soccer field), di lapangan kerja (on the worksite), etc.

How do we know if this means are worn, were worn, or will be worn? There’s no tense.

Indonesian verbs don’t change form for tense like English verbs do. Dipakai itself is tenseless; the time is understood from context or extra words.

Possible interpretations, depending on context:

Those boots are also worn when it rains heavily on the field. (present, habitual)
Those boots were also worn when it rained heavily on the field. (past)
Those boots will also be worn when it rains heavily on the field. (future plan/habit)

To make the time explicit, you can add adverbs:

Dulu sepatu bot itu dipakai... = In the past, those boots were worn...
Sekarang sepatu bot itu dipakai... = Now those boots are worn...
Nanti sepatu bot itu akan dipakai... = Later / in the future those boots will be worn...

Why is there no subject like we or they? Is that normal?

Yes, it’s normal. Indonesian often:

Drops the subject when it’s obvious from context, and
Uses the passive (dipakai) when the doer is not important.

In English you might think in terms of:

We also wear those boots when it rains heavily on the field.

Indonesian expresses the same idea by focusing on the boots:

Sepatu bot itu dipakai juga ketika hujan deras di lapangan.
= Literally: Those boots are also worn when it rains heavily on the field.

If you want to include the subject, you can use either active or passive with an explicit agent:

Active: Kami juga memakai sepatu bot itu ketika hujan deras di lapangan.
Passive with agent: Sepatu bot itu juga dipakai oleh kami ketika hujan deras di lapangan.

Can itu be omitted? What changes if I just say Sepatu bot dipakai juga...?

Yes, you can omit itu, but the meaning becomes more general:

Sepatu bot itu dipakai juga...
- Refers to specific boots already known in the conversation.
- Roughly: “Those boots are also worn...” / “The boots are also worn...”
Sepatu bot dipakai juga...
- More general: boots in general, not particular ones.
- Roughly: “Boots are also worn...” (as a general statement about what people do)

So itu adds definiteness and points to specific boots.

Could I say Sepatu bot itu dipakai ketika hujan deras juga di lapangan? Does the position of juga change the meaning?

You can say it, but the position of juga becomes ambiguous and sounds a bit awkward.

Sepatu bot itu juga dipakai ketika hujan deras di lapangan.
→ juga clearly modifies dipakai (“are also worn”).
Sepatu bot itu dipakai juga ketika hujan deras di lapangan.
→ Still mostly understood as “also worn (when it’s raining heavily on the field)”.
Sepatu bot itu dipakai ketika hujan deras juga di lapangan.
→ Now juga appears to modify hujan deras or the whole hujan deras di lapangan phrase, which is strange. It can sound like “when it also rains heavily on the field”, which is not what you want.

For clear, natural Indonesian, keep juga close to dipakai:

Sepatu bot itu juga dipakai ketika hujan deras di lapangan. ✔
Sepatu bot itu dipakai juga ketika hujan deras di lapangan. ✔ (less common but OK)