kono repooto ha mae no hodo nagaku nai node, konya no uti ni yomesou desu.

It means as the previous one.

More literally:

• 前の = the previous one / the earlier one
• the noun レポート is omitted because it is obvious from context
• ほど is the comparison word used in patterns like
  A は B ほど ... ない = A is not as ... as B

So:

• このレポートは前のほど長くない
  = This report is not as long as the previous one

A fully expanded version would be:

• このレポートは前のレポートほど長くない

Because 長い is an い-adjective, and い-adjectives make the negative this way:

• remove the final い
• add くない

So:

• 長い → 長くない

This is the normal negative form of an い-adjective.

Other examples:

• 高い → 高くない
• 新しい → 新しくない
• 難しい → 難しくない

In this sentence, ほど marks the standard of comparison.

The pattern is:

• A は B ほど adjective-negative
• A is not as adjective as B

So here:

• このレポートは前のほど長くない
• This report is not as long as the previous one

Important point: in this pattern, ほど is usually used with a negative predicate.

Examples:

• 今日は昨日ほど寒くない
  = Today is not as cold as yesterday.
• 彼は兄ほど背が高くない
  = He is not as tall as his older brother.

は marks このレポート as the topic: as for this report...

That makes sense because the speaker is talking about this report and then comparing it with the previous one.

It can also give a slight contrastive feeling:

• this report, unlike the previous one, is not so long

So は is very natural here.

Both can mean because, but ので sounds a bit more explanatory and softer.

Here:

• 長くないので、今夜のうちに読めそうです
• Since it is not as long as the previous one, it seems I can read it tonight

Compared with から:

• 長くないから can sound a little more direct or personal
• 長くないので sounds a little more neutral and descriptive

In many situations, both are possible, but ので fits the calm explanatory tone of this sentence well.

今夜のうちに means:

• while it is still tonight
• before tonight is over
• sometime tonight, before the night ends

The key expression is ～のうちに.

This often means doing something within a certain time span before it passes or changes.

Examples:

• 熱いうちに食べてください
  = Please eat it while it is still hot.
• 若いうちにたくさん経験したほうがいい
  = It is better to have many experiences while you are young.
• 今夜のうちに終わらせたい
  = I want to finish it by tonight / before tonight is over.

So 今夜のうちに is not just tonight in a general sense; it emphasizes within tonight’s remaining time.

The に marks the time limit or target point for the action.

In ～のうちに, the whole phrase works like an adverb meaning:

• during
• within
• before the end of

So:

• 今夜のうちに読む
• read it before tonight is over

The に is part of this very common pattern.

読めそうです means something like:

• It looks like I can read it
• I seem likely to be able to read it
• It seems manageable to read

Breakdown:

• 読む = to read
• 読める = can read / be able to read
• 読めそう = seems like one can read it

So the speaker is not just saying I will read it, but rather it seems possible / manageable for me to read it.

Because these are two different uses of そう.

1. Verb stem + そう
   This often means looks like it will do that action.

• 読みそう = looks like someone will read it

2. Potential form + そう
   This means looks like someone can do it.

• 読めそう = looks like someone can read it

So:

• 読みそうです = It looks like I will read it
• 読めそうです = It looks like I can read it

In your sentence, the second meaning is needed, because the idea is that the report is short enough to make reading it tonight possible.

It is not 100% certain. It gives a sense of probability or appearance.

It suggests:

• based on the length, it seems possible
• the speaker thinks it is manageable
• but it is not a firm guarantee

So 読めそうです is softer than:

• 読めます = I can read it
• 今夜のうちに読みます = I will read it tonight

It sounds more like:

• I should be able to read it tonight
• It looks like I can get through it tonight

Here it means previous or earlier, not front.

前 can mean different things depending on context:

• front
• before
• previous

In 前のレポート, it means:

• the previous report
• the earlier report

So context tells you which meaning is intended.

Yes. The omitted noun is almost certainly レポート.

Japanese very often leaves out repeated nouns when they are obvious from context.

So:

• 前のほど長くない

is understood as:

• 前のレポートほど長くない

This omission makes the sentence sound natural and less repetitive.

The sentence breaks down like this:

• このレポートは = as for this report
• 前のほど長くないので = since it is not as long as the previous one
• 今夜のうちに = before tonight is over
• 読めそうです = it seems I can read it

So the grammar flow is:

• topic
• comparison in negative form
• reason with ので
• time expression
• potential + そうです

It is a very natural sentence pattern for explaining why something seems doable.

Yes. A more explicit version would be:

• このレポートは前のレポートほど長くないので、今夜のうちに読めそうです。

That version includes the repeated noun レポート after 前の.

The original sentence is more natural in everyday Japanese because repeated words are often omitted when they are clear.