Mifumo ya jengo ina kinga dhidi ya maji.

Mifumo means systems. Its singular form is mfumo, meaning system.

This is a common noun class pair in Swahili:

• singular: mfumo
• plural: mifumo

So mifumo ya jengo means building systems or more literally systems of the building.

Because the connector -a changes form to agree with the noun it belongs to, and here it belongs to mifumo.

Since mifumo is in the m-/mi- plural class, the connector becomes ya:

• mfumo wa jengo = system of the building
• mifumo ya jengo = systems of the building

So ya is correct because the head noun is mifumo, not jengo.

Because Swahili verb agreement follows noun class, not just simple singular/plural the way English does.

Mifumo is plural, but it belongs to a noun class that takes the subject prefix i-.
So:

• mfumo una... = the system has...
• mifumo ina... = the systems have...

To an English speaker, ina may look singular, but in Swahili it is the correct agreement for mifumo.

Yes. In this sentence, ina means has.

It is made of:

• i- = subject marker agreeing with mifumo
• -na = have / with

So mifumo ina kinga literally means the systems have protection.

Kinga means protection, defense, resistance, or sometimes immunity, depending on context.

In this sentence, kinga dhidi ya maji means something like:

• protection against water
• water resistance
• waterproofing (depending on context)

So here kinga is not medical immunity; it is protective resistance.

Dhidi ya is a fixed expression meaning against.

So:

• kinga dhidi ya maji = protection against water

This is a very common pattern in Swahili:

• ulinzi dhidi ya wizi = protection against theft
• chanjo dhidi ya ugonjwa = vaccine against disease
• kinga dhidi ya maji = protection against water

It is best learned as one phrase: dhidi ya.

Because the phrase is talking about the systems of a building or of the building, not necessarily of multiple buildings.

So:

• mifumo ya jengo = building systems / systems of a building
• mifumo ya majengo = systems of buildings

Swahili often uses a singular noun here when English might also use a singular noun in an attributive sense, like building systems.

Because Swahili does not normally use articles like the or a/an.

So jengo can mean:

• a building
• the building
• sometimes just building in a general sense

The exact meaning depends on context. That is normal in Swahili.

Maji is grammatically treated like a class 6 noun, and its form looks plural, but in meaning it usually works as a mass noun: water.

So even though it has a plural-looking form, here it simply means water, not waters.

This is one of those nouns that English speakers should learn as a vocabulary item rather than trying to force it into English singular/plural logic.

A fairly literal breakdown is:

• Mifumo = systems
• ya jengo = of the building / building
• ina = has / have
• kinga = protection
• dhidi ya maji = against water

So the literal sense is:

Building systems have protection against water.

The word order is actually fairly close to English here.

Yes, that is a reasonable natural translation depending on context.

The Swahili sentence literally says the systems have protection against water, but in smoother English that could become:

• The building systems are water-resistant
• The building systems are protected against water
• The building systems have water protection

Which version is best depends on the context: technical writing, engineering, product specs, and so on.

You would say:

Mfumo wa jengo una kinga dhidi ya maji.

Notice the changes:

• mifumo → mfumo
• ya → wa
• ina → una

That is because the noun class agreement changes when you go from singular to plural.