oritatamizitensya ha karui.

It is read:

おりたたみじてんしゃ は かるい。

Broken down:

• 折りたたみ = おりたたみ
• 自転車 = じてんしゃ
• は = pronounced wa here, even though it is written with は
• 軽い = かるい

So the full reading is:

おりたたみじてんしゃ は かるい。

折りたたみ自転車 is a compound noun meaning folding bicycle.

It breaks down like this:

• 折りたたみ = folding / fold-up
• 自転車 = bicycle

So together:

• 折りたたみ自転車 = folding bicycle

In Japanese, it is very common to put nouns and noun-like modifiers directly before another noun, so this kind of long compound is normal.

は marks the topic of the sentence.

So:

• 折りたたみ自転車は = as for folding bicycles
• 軽い = are light / is light

A very literal sense is:

• As for folding bicycles, they are light.

In natural English, you would usually just say Folding bicycles are light or A folding bicycle is light, depending on context.

When は is used as the topic particle, it is pronounced wa.

This is just a special rule for certain particles in Japanese:

• は is written ha, but as a particle it is pronounced wa
• へ is written he, but as a particle it is pronounced e

So in this sentence:

• written: 折りたたみ自転車は軽い
• read: おりたたみじてんしゃ wa かるい

Japanese sentences often put the main predicate at the end.

Here:

• 折りたたみ自転車は = topic
• 軽い = predicate

So the structure is basically:

Topic + description

That is why light comes at the end in Japanese, even though in English it appears earlier:

• Japanese: 折りたたみ自転車は軽い
• Literal order: As for folding bicycles, light
• Natural English: Folding bicycles are light

Because 軽い is an い-adjective, and it can end a sentence by itself in plain style.

So:

• 軽い。 = plain style
• 軽いです。 = polite style

Both are grammatically correct.

Compare:

• 折りたたみ自転車は軽い。 = plain, casual
• 折りたたみ自転車は軽いです。 = polite

Unlike nouns and な-adjectives, い-adjectives do not need です to be grammatical.

Yes. 軽い is an い-adjective.

That means:

• it ends in -い
• it can directly describe something
• it can end a sentence on its own

Examples:

• 軽い自転車 = a light bicycle
• 自転車は軽い = the bicycle is light

This is different from a noun or a な-adjective, which would need different grammar.

Here it means light in weight.

軽い usually means:

• light
• not heavy

It does not mean bright/light in the sense of illumination here.

For example:

• このかばんは軽い。 = This bag is light.
• 軽い自転車 = a light bicycle

So in this sentence, it means the bicycle is easy to carry because it is not heavy.

Japanese usually does not use articles like a, an, or the.

So 折りたたみ自転車 could mean:

• a folding bicycle
• the folding bicycle
• folding bicycles

The exact meaning depends on context.

That is why the sentence could be understood in different ways in English, such as:

• A folding bicycle is light.
• The folding bicycle is light.
• Folding bicycles are light.

Without more context, Japanese often leaves that open.

It could be either, depending on context.

Japanese often leaves number unspecified unless it is important.

So 折りたたみ自転車は軽い can mean:

• A folding bicycle is light
• The folding bicycle is light
• Folding bicycles are light

If someone is speaking generally about the category, it likely means:

• Folding bicycles are light

If they are pointing at a specific bike, it likely means:

• This/The folding bicycle is light

Yes, but the nuance would change.

• 折りたたみ自転車は軽い。
  = As for folding bicycles, they are light.
  This sounds like a general statement or topic.

• 折りたたみ自転車が軽い。
  = It is the folding bicycle that is light / The folding bicycle is light
  This can sound more like identifying or emphasizing the subject.

In beginner terms:

• は = marks the topic
• が = marks the subject more directly, often with focus or contrast implications

In this sentence, は is very natural if you are making a general statement.

They are different structures.

• 折りたたみ自転車は軽い。
  = The folding bicycle is light / Folding bicycles are light
  This is a full sentence.

• 軽い折りたたみ自転車
  = a light folding bicycle
  This is just a noun phrase, not a complete sentence.

So:

• 軽い after the noun phrase can finish the sentence
• 軽い before the noun directly modifies it

折りたたみ comes from the verb 折りたたむ, which means to fold up.

In this sentence, 折りたたみ functions like a noun or noun-like modifier in the compound:

• 折りたたみ自転車 = folding bicycle

This is very common in Japanese. A verb stem or related form can become part of a compound noun.

So you do not need to think of it as a full verb here. It is simply part of the noun folding bicycle.

Yes. Normal Japanese is written without spaces.

So the standard writing is:

折りたたみ自転車は軽い。

Spaces are sometimes added in beginner materials only to make the structure easier to see:

• 折りたたみ自転車　は　軽い。

That spacing is for learning, not normal writing.