ame ga tuduku to, beranda ni hosenai node, kansouki ga totemo yaku ni tatimasu.

In this sentence, が marks 雨 as the thing that is doing the action 続く.

• 雨が続く = rain continues
• 雨は続く would sound more contrastive, like as for the rain, it continues or the rain, at least, continues

Here, the speaker is just stating the condition naturally, so が is the normal choice.

続く means to continue or to keep going.

So:

• 雨が続く = the rain continues
• more naturally in English: when it keeps raining / when rainy weather continues

It does not mean one single moment of rain. It suggests rain over a period of time.

Before と used as a conditional, Japanese uses the plain form.

So:

• 続くと = if/when it continues
• 続きますと is possible in very formal speech, but not the normal everyday way here

This is very common in polite sentences: even if the main sentence ends politely, earlier clauses often stay in plain form.

So the structure is:

• 雨が続くと = conditional clause in plain form
• 役に立ちます = main clause in polite form

Here, と means when or if.

It connects a condition with a natural result:

• 雨が続くと、ベランダに干せない = When it keeps raining, you can't hang things out on the balcony

This と is often used when the result is something habitual, natural, or expected.

It is less about a personal decision and more about a regular consequence.

With 干す in the sense of hang out to dry, に is very natural for the place where something is put or hung.

• ベランダに干す = hang it on the balcony / put it out on the balcony to dry

Using で would focus more on the location where an action happens, but with 干す, Japanese commonly treats the balcony as the destination/place where the laundry is placed, so に is the usual choice.

So ベランダに干す is the standard expression.

干せない is the potential negative form of 干す.

• 干す = to hang out to dry
• 干せる = can hang out to dry
• 干せない = cannot hang out to dry

So this sentence is not saying I do not hang it out by choice.
It means I can't hang it out, because the weather makes it impossible or impractical.

The object is omitted because it is understood from context.

Japanese often leaves out things that are obvious. Here, the omitted object is something like:

• 洗濯物 = laundry
• 服 = clothes

So the full idea is:

• ベランダに洗濯物を干せないので = because I can't hang the laundry out on the balcony

But saying the object is unnecessary if everyone already knows the topic is drying laundry.

ので means because, and it often sounds a little softer, more explanatory, and less blunt than から.

Here:

• ベランダに干せないので、乾燥機がとても役に立ちます = Because I can't hang things out on the balcony, the dryer is very useful

If you used から, it would still be correct:

• ベランダに干せないから、乾燥機がとても役に立ちます

But ので sounds a bit more like calmly giving a reason.

Because ので attaches to the plain form of a verb or adjective.

Here the verb phrase is:

• 干せない = plain negative form

Then:

• 干せないので = because [I] can't hang it out to dry

This is normal grammar:

• verb plain form + ので
• 食べるので = because I eat / will eat
• 食べないので = because I do not eat / will not eat

乾燥機 means dryer or drying machine.

In this sentence, it most naturally means a clothes dryer, because the earlier part talks about not being able to hang laundry out on the balcony.

So the flow is:

• it keeps raining
• you can't dry laundry outside
• therefore the dryer is useful

役に立つ is a set expression meaning to be useful or to be helpful.

Literally:

• 役 = use, service, function, benefit
• に立つ = to stand in / serve for

But you should learn 役に立つ as one chunk:

• 役に立つ = to be useful
• 役に立ちます = polite form

So:

• 乾燥機がとても役に立ちます = The dryer is very useful

Both exist, but 役に立つ is the more common and basic expression for to be useful.

• 役に立つ = standard phrase, very common
• 役立つ = also means to be useful, but it can sound a bit more compact or written depending on context

For a learner, it is best to treat 役に立つ as the main expression to remember.

とても means very.

It modifies 役に立ちます:

• とても役に立ちます = is very useful

So the sentence is saying not just that the dryer is useful, but that it is really useful in this situation.

This is completely normal in Japanese.

In a sentence with subordinate clauses:

• earlier clauses often use plain forms
• the final clause shows the overall politeness level

So:

• 雨が続くと
• ベランダに干せないので
• 乾燥機がとても役に立ちます

Only the final verb needs to be polite for the whole sentence to sound polite.

Yes. In fact, that is often the better interpretation.

Because 続く means continue, the nuance is not just if it rains once, but rather:

• when rain continues
• when it keeps raining
• when rainy weather goes on for days

That continuing sense is important, because one short rain shower would not necessarily stop someone from drying clothes outside for a long time.