כשאין חשמל, התנור והמקפיא לא עובדים.

כשאין is made of two parts:

• כש־ = when
• אין = there is no / there isn't

So כשאין means when there is no...

It is written as one word because כש־ attaches directly to the next word in Hebrew.
A rough pronunciation is kshe-EIN.

Because אין is the normal Hebrew way to say that something does not exist / is not present in the present tense.

• יש חשמל = there is electricity
• אין חשמל = there is no electricity

You do not normally say לא יש חשמל in standard Hebrew.
By contrast, לא is used to negate verbs and many other predicates:

• לא עובדים = do not work / are not working

Because חשמל here is being used as a general mass noun, like electricity in English.

Hebrew often leaves mass nouns and abstract nouns without ה־ when speaking generally:

• יש מים = there is water
• אין זמן = there is no time
• אין חשמל = there is no electricity

Using החשמל here would sound like you were referring to some specific, already-identified electricity, which is not what this sentence is doing.

Because both nouns are definite: the oven and the freezer.

In Hebrew, if two coordinated nouns are both definite, each one usually gets its own ה־:

• התנור והמקפיא

This is more natural than trying to put the definiteness on only one of them.
So Hebrew is being very literal here: the oven and the freezer.

Because the subject is two things together:

• התנור = the oven
• המקפיא = the freezer

Together they form a plural subject, so the verb/predicate must also be plural:

• one item: התנור לא עובד
• two items: התנור והמקפיא לא עובדים

Because both תנור and מקפיא are masculine nouns.

In Hebrew, present-tense verb forms agree in gender and number. Since the subject is plural and masculine, Hebrew uses עובדים.

Compare:

• masculine singular: עובד
• feminine singular: עובדת
• masculine plural: עובדים
• feminine plural: עובדות

Yes. In Hebrew, עובד / עובדים can describe both:

• people who are working
• machines/appliances that are functioning

So with appliances, לא עובדים means don’t work / aren’t working / aren’t functioning.

This is very common Hebrew:

• המחשב לא עובד = the computer isn’t working
• המזגן לא עובד = the air conditioner isn’t working

Hebrew usually does not use a separate present-tense word for am / is / are.

Instead, the present form itself does the job:

• עובדים can mean work or are working, depending on context.

So:

• לא עובדים can mean do not work
• or are not working

Hebrew present tense often covers both the simple and progressive meanings that English separates.

Yes, but the nuance changes a little.

• כשאין חשמל = when/whenever there is no electricity
• אם אין חשמל = if there is no electricity

In this sentence, כשאין sounds like a general situation: whenever there’s no power, the oven and freezer don’t work.
Using אם would sound more conditional or hypothetical.

Yes. That word order is also grammatical.

Both are possible:

• כשאין חשמל, התנור והמקפיא לא עובדים.
• התנור והמקפיא לא עובדים כשאין חשמל.

Starting with כשאין חשמל puts the condition first, a bit like English When there is no electricity, ...
The comma is natural when the sentence begins with that when... clause.