יש הרבה מודעות באינטרנט, אבל לא כל מודעה טובה כמו שהיא נראית.

יש is the Hebrew way to say there is or there are.

So:

• יש הרבה מודעות באינטרנט = There are many ads on the internet

Hebrew often uses יש to introduce the existence of something. Unlike English, Hebrew does not need a separate there in this structure.

In Hebrew, words like הרבה (many / a lot of) normally come before the noun:

• הרבה מודעות = many ads
• הרבה אנשים = many people
• הרבה זמן = a lot of time

So הרבה מודעות is the normal word order.

The singular is מודעה = ad / advertisement.

So:

• מודעה = one ad
• מודעות = ads

This is a feminine noun, which matters because other words describing it must also be feminine.

Here, לא כל מודעה means not every ad.

Literally:

• לא = not
• כל = every / all
• מודעה = ad

So the idea is:

• not every ad is good as it seems

This is more natural in English as not every ad is as good as it looks.

If Hebrew wanted to say not all ads, it would more naturally use a plural structure such as לא כל המודעות or another wording depending on context.

Because מודעה is a feminine singular noun, the adjective must match it.

So:

• מודעה טובה = a good ad
• not מודעה טוב

Agreement is very important in Hebrew. Adjectives usually match the noun in:

• gender
• number
• sometimes definiteness

Here:

• מודעה = feminine singular
• טובה = feminine singular form of good

In the present tense, Hebrew usually does not use a word for is / are.

So:

• המודעה טובה literally = the ad good
• natural English = the ad is good

That is normal Hebrew grammar.

Hebrew does use forms of to be in the past and future, but in the present tense they are usually omitted.

כמו means like or as.

In this sentence:

• כמו שהיא נראית = as it appears / as it looks

So:

• לא כל מודעה טובה כמו שהיא נראית = Not every ad is as good as it looks

Here כמו introduces the comparison.

שהיא is made of two parts:

• ש־ = that / which / as
• היא = she / it (feminine singular)

Together, שהיא means something like:

• that it is
• as it
• which it

In this sentence, it refers back to מודעה, which is feminine. Since מודעה is feminine singular, Hebrew uses היא.

So כמו שהיא נראית literally feels like:

• as she/it appears

But in natural English, we say:

• as it looks
• as it appears

Because Hebrew nouns have grammatical gender.

מודעה is a feminine noun, so when Hebrew refers back to it, it uses feminine forms:

• היא = feminine singular pronoun
• נראית = feminine singular verb form

Even though an ad is not biologically female, Hebrew grammar still treats it as feminine because the noun itself is feminine.

נראית means looks, appears, or seems.

It comes from the verb להיראות = to seem / to appear / to look.

Because the subject is feminine singular (מודעה), the form is:

• נראית = feminine singular present

Compare:

• הוא נראה = he/it looks
• היא נראית = she/it looks
• הם נראים = they look (masculine/mixed)
• הן נראות = they look (feminine)

Hebrew present-tense verb forms still agree with the subject in gender and number.

So even in the present tense, Hebrew distinguishes:

• masculine singular
• feminine singular
• masculine plural
• feminine plural

Since the subject here is היא referring to מודעה, the verb must be feminine singular:

• היא נראית

If the noun were masculine singular, it would be:

• כמו שהוא נראה = as it looks (for a masculine noun)

באינטרנט means on the internet or on the Internet.

It is made from:

• ב־ = in / on / at
• אינטרנט = internet

So literally it is something like in/on the internet.

In English we usually say on the internet, but Hebrew commonly uses ב־ in this kind of expression.

Because the meaning is general: not every ad, not not every the ad.

Hebrew uses כל with a noun to mean every or each, and that noun is often indefinite in this structure:

• כל יום = every day
• כל אדם = every person
• כל מודעה = every ad

So לא כל מודעה is the normal way to say not every ad.

Yes. The Hebrew phrase has a slightly broader sense than the most literal English version.

Depending on context, it can mean:

• as it looks
• as it appears
• as it seems

So the sentence suggests that an ad may give a good impression, but in reality it may not be that good.

It breaks down like this:

• יש הרבה מודעות באינטרנט = There are many ads on the internet
• אבל = but
• לא כל מודעה טובה כמו שהיא נראית = not every ad is as good as it looks

So the full sentence contrasts two ideas:

1. there are many ads online
2. appearances can be misleading

This kind of sentence is very common in Hebrew: a simple statement, followed by אבל to introduce a contrast.