Mlango wa chuma umefungwa sasa.

A simple breakdown is:

• Mlango = door
• wa chuma = of metal / iron
• umefungwa = is closed / has been closed
• sasa = now

So the structure is roughly:

• Mlango = the thing being talked about
• wa chuma = describes what kind of door it is
• umefungwa = tells its current state
• sasa = adds the time idea now

Because mlango belongs to a noun class that uses the connective wa in the singular.

In Swahili, of changes form depending on the noun class of the noun before it.
Since mlango is a singular noun in the m-/mi- class, the connector is wa:

• mlango wa chuma = door of metal
• mti wa matunda = tree of fruit

If the noun were from another class, the form of of would change.

Umefungwa contains several pieces:

• u- = subject marker agreeing with mlango
• -me- = perfect marker
• -fungwa = passive form of the verb root -funga

So:

• -funga = close, shut, fasten
• -fungwa = be closed, be shut, be fastened
• umefungwa = it has become closed / it is closed

With objects like doors, this often translates naturally as is closed.

Because umefunga and umefungwa mean different things.

• umefunga = it has closed / it has shut something or sometimes you have closed, depending on context
• umefungwa = it has been closed / it is closed

The ending -wa makes the verb passive. Since the sentence is describing the state of the door, the passive form is the natural choice.

It can suggest either closed, shut, or locked, depending on context.

The verb -funga often covers a range that in English may be expressed by:

• close
• shut
• fasten
• sometimes lock

So Mlango wa chuma umefungwa sasa could mean:

• The metal door is closed now
• The iron door is shut now
• in some contexts, The metal door is locked now

If you need to be very specific, context or extra words help.

Mlango is usually treated as a singular noun in the m-/mi- noun class.

That matters because noun class affects agreement in Swahili. It determines forms like:

• the connector wa
• the subject marker u-

So in this sentence:

• mlango wa chuma
• mlango umefungwa

If it were plural, it would be milango, and the agreement would change.

The plural is:

Milango ya chuma imefungwa sasa.

Changes:

• mlango → milango = door → doors
• wa → ya
• u- → i-

So:

• Mlango wa chuma umefungwa sasa = The metal door is closed now
• Milango ya chuma imefungwa sasa = The metal doors are closed now

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

So mlango can mean:

• a door
• the door

Which one sounds best depends on context. In a full situation, listeners usually already know whether the speaker means a specific door or just a door in general.

Yes, sasa can appear in different places, though the version you have is very natural.

• Mlango wa chuma umefungwa sasa.
• Sasa mlango wa chuma umefungwa.

Both are possible.

Putting sasa at the end often gives a natural now/currently feeling. Putting it at the beginning can slightly emphasize the time.

It can mean both, depending on context.

• literally: iron
• more broadly: metal

So mlango wa chuma may be understood as:

• iron door
• metal door

If the exact material matters, context usually makes it clear.

Mostly a state resulting from an action.

Umefungwa is perfect in form, but in many everyday contexts it is best translated as a present state:

• is closed now
• has been closed now

So the focus is usually not on the act of closing, but on the fact that the door is now in the closed state.

A rough guide:

• Mlango ≈ m-LAHN-go
• wa ≈ wah
• chuma ≈ CHOO-ma
• umefungwa ≈ oo-meh-FOONG-wah
• sasa ≈ SAH-sah

A few helpful notes:

• Swahili vowels are usually clear and simple:
  • a as in father
  • e as in bed but often cleaner
  • i as in machine
  • o as in more without a glide
  • u as in rule
• ngw in umefungwa is pronounced fully.
• Stress in Swahili is usually on the second-to-last syllable:
  • mlaNGo
  • CHUma
  • umeFUNGwa
  • SAsa

Yes, but it means something different.

• umefungwa sasa = is closed now / has been closed now
• unafungwa sasa = is being closed now

So:

• umefungwa focuses on the resulting state
• unafungwa focuses on the action happening right now

That is an important difference.

Yes, it is natural and grammatically normal.

It sounds like something you might say when giving an update about the status of a door, especially if the fact that it is made of metal matters:

• maybe for security
• maybe to identify which door
• maybe in a building or gate context

Without wa chuma, the simpler sentence Mlango umefungwa sasa would also be very natural if the material does not need to be mentioned.