בלי בקרת אקלים ואוורור יכול להיות עובש.

בלי means without.

In this sentence, it introduces what is missing:

• בלי בקרת אקלים ואוורור = without climate control and ventilation

A very common pattern in Hebrew is:

• בלי + noun
• בלי + noun + ו + noun

For example:

• בלי מים = without water
• בלי אוכל ושתייה = without food and drink

A slightly more formal synonym is ללא, but בלי is very common in everyday Hebrew.

This is a construct chain in Hebrew, called סמיכות.

• בקרה = control / monitoring
• אקלים = climate
• בקרת אקלים = climate control

When two nouns are linked this way, the first noun often changes form. Here:

• בקרה becomes בקרת

So בקרת אקלים literally works like control of climate, which is the Hebrew way to say climate control.

This is very common in Hebrew:

• חדר שינה = bedroom
• בית ספר = school
• תעודת זהות = identity card

אוורור means ventilation or airing out.

It comes from the root related to air:

• אוויר = air
• לאוורר = to ventilate / air out
• אוורור = ventilation

So:

• בקרת אקלים ואוורור = climate control and ventilation

Because בקרת אקלים ואוורור is not the subject of the sentence. It is part of a prepositional phrase beginning with בלי:

• בלי בקרת אקלים ואוורור = without climate control and ventilation

The main part of the sentence is:

• יכול להיות עובש = there can be mold / mold can occur

Here יכול להיות is being used in an impersonal way, similar to English there can be. In that kind of structure, Hebrew often uses the default masculine singular form:

• יכול להיות... = it can be / there can be / it’s possible that...

So the verb is not agreeing with בקרת אקלים ואוורור.

Literally, יכול להיות means can be or may be.

In this sentence, though, it sounds more natural in English as:

• there can be mold
• mold can develop
• you can get mold

So this is not really saying the mold is able to exist in a literal, personal sense. It is an impersonal Hebrew expression meaning that something is possible or may happen.

Very common uses:

• יכול להיות = maybe / it could be / it may be
• יכול להיות שיש בעיה = there may be a problem
• יכול להיות גשם = there could be rain

It could use יש, but it does not have to.

Compare:

• יכול להיות עובש = there can be mold / mold may occur
• יכול להיות שיש עובש = it may be that there is mold

The version without יש is more compact and direct. It sounds like a general statement about what can happen under those conditions.

So:

• בלי בקרת אקלים ואוורור יכול להיות עובש
  = Without climate control and ventilation, there can be mold.

If you added שיש, it would shift slightly toward it may be that there is mold, which is a bit different in feel.

Because the sentence is making a general statement, not talking about specific known things.

• בקרת אקלים = climate control, in general
• אוורור = ventilation, in general
• עובש = mold, in general

If you added ה־, it would sound more specific:

• בקרת האקלים = the climate control
• האוורור = the ventilation
• העובש = the mold

But here the meaning is broad: if a place lacks climate control and ventilation, mold may develop.

Also note: in a construct chain like בקרת אקלים, definiteness is marked on the second noun:

• בקרת אקלים = climate control
• בקרת האקלים = the climate control

Usually, עובש is treated like a mass noun, much like mold in English.

So Hebrew normally says:

• יש עובש = there is mold
• יכול להיות עובש = there can be mold

You would not normally treat it like one mold / two molds in everyday usage.

If you want to talk about separate spots or patches, Hebrew would usually use another noun, such as:

• כתמי עובש = mold stains / mold spots

Yes. Both are possible.

• בלי בקרת אקלים ואוורור = without climate control and ventilation
• בלי בקרת אקלים ובלי אוורור = without climate control and without ventilation

The second version is a bit more explicit because it repeats בלי. The first version is more compact and very natural.

This is similar to English:

• without climate control and ventilation
• without climate control and without ventilation

Both work, but the repeated version can add emphasis or clarity.

Yes. Hebrew often allows subjectless or impersonal constructions where English would need it or there.

Here:

• יכול להיות עובש

functions like:

• there can be mold
• it is possible for there to be mold

English needs a dummy subject like there or it, but Hebrew often does not.

That is very normal Hebrew style.

A natural way to understand it is:

• Without climate control and ventilation, there can be mold.
• Without climate control and ventilation, mold can develop.
• If there’s no climate control and ventilation, mold can form.

The Hebrew is concise and slightly general in tone. It sounds like a warning or explanation of conditions that can lead to mold.