Tutakunywa chai tukizungumza nyumbani.

In Swahili the subject is usually built into the verb, not a separate word.

• tu- = we
• -ta- = future tense (will)
• kunywa = to drink

So tutakunywa literally breaks down as:

• tu- (we) + -ta- (future) + kunywa (drink)
  → we will drink

Because tu- already means we, you normally don’t add an extra separate word for we.

Think of tutakunywa as tuta- + kunywa:

• tu- = we (subject prefix)
• -ta- = future tense marker (will)
• kunywa = to drink

So:

• tutakunywa = we will drink

The important pattern for verbs is:

subject prefix + tense marker + verb stem

Here:

• subject prefix = tu-
• tense = -ta- (future)
• verb stem (infinitive without the initial ku- for most verbs, though kunywa is a bit irregular and you still see ku- inside).

tukizungumza is built like this:

• tu- = we (subject)
• -ki- = “when / while / as (doing something)”
• zungumza = talk, speak

So:

• tukizungumza = while we are talking / as we talk

The -ki- marker creates a kind of “when/while …” clause.
In general:

• tukifanya = while/when we do
• tukila = while/when we eat
• tukizungumza = while/when we talk

So the sentence is literally We will drink tea, while we-talk (tukizungumza) at home.

Tutakunywa chai na tutaongea nyumbani is understandable, but the nuance is a bit different:

• Tutakunywa chai tukizungumza nyumbani
  → We will drink tea while we talk at home (simultaneous actions).

• Tutakunywa chai na tutaongea nyumbani
  → We will drink tea and we will talk at home (just two actions, not clearly “at the same time”).

Using tuki- (as in tukizungumza) is the idiomatic way to express “while/as we …”.
Using na plus another full verb is more like simple “and …”, without emphasizing simultaneity.

The -ki- here is sometimes called a “circumstantial” or “consecutive” marker. In many everyday contexts it means:

• when
• while
• as

Examples:

• Nikila, usinisumbue. → When/while I’m eating, don’t disturb me.
• Wakicheza, walivunjika mguu. → When they were playing, they broke a leg.

In tukizungumza, -ki- shows that talking is the background action happening at the same time as drinking tea. Context tells you whether to translate it as when or while; here while sounds most natural.

Nyumba = house, home (basic noun).
Nyumbani = at home / in the house.

The -ni on many nouns is a locative ending, meaning in, at, or to that place.

Examples:

• shule → school
  shuleni → at school
• kanisa → church
  kanisani → at church
• nyumba → house
  nyumbani → at home / in the house

So nyumbani already includes the idea of “at”, so you usually don’t need an extra preposition like “at” or “in” in Swahili.

You can, but the nuance is a bit different:

• nyumbani
  → the natural, everyday way to say at home / in the house. Very common and idiomatic.

• katika nyumba or kwenye nyumba
  → literally in the house / inside the house. Grammatically fine, but it sounds a bit more literal or specific to a particular house, and less like the general idea of “at home”.

In your sentence, nyumbani is exactly what most speakers would choose.

Both are grammatically possible; the difference is in emphasis and typical usage:

• tukizungumza nyumbani
  → Slightly more natural order here: while we talk at home.

• nyumbani tukizungumza
  → Puts a bit more focus on nyumbani (the place). Could sound like: At home, while we talk … (depending on the rest of the sentence).

In this short sentence, Tutakunywa chai tukizungumza nyumbani is the most neutral and natural word order.

Both kuongea and kuzungumza mean to talk / to speak, and in everyday conversation they often overlap.

• kuongea: very common, slightly more informal in some regions.
• kuzungumza: also common, sometimes feels a bit more “proper” or formal in some contexts, but not always.

You can absolutely say:

• Tutakunywa chai tukiongea nyumbani.

This is natural and means essentially the same thing:
We will drink tea while we talk at home.

You can keep the same structure and still be understood, but if you really want to highlight the continuous aspect, you can use tutakuwa tukinywa:

• Tutakuwa tukinywa chai tukizungumza nyumbani.
  → We will be drinking tea while we are talking at home.

Breakdown:

• tutakuwa = we will be
• tukinywa = while we are drinking (same tu- + -ki-)
• tukizungumza = while we are talking

In everyday speech, though, Tutakunywa chai tukizungumza nyumbani already naturally implies a simultaneous, ongoing action, so it’s usually enough.