उस यात्रा में पिता भी साथ जाएँगे, और हम वहाँ रहेंगे।

उस is the oblique form of वह (that / he / she).

In Hindi, words like वह change form before many postpositions such as में, से, को, पर.
So:

• वह यात्रा = that trip/journey
• उस यात्रा में = in that trip/journey

So उस is used because it comes before में.

में usually means in, inside, during, within the context of.

So उस यात्रा में literally means in that journey/trip. Depending on context, English might translate it more naturally as:

• on that trip
• during that journey

Hindi often uses में where English uses on or during.

पिता means father.

Hindi often leaves out possessives like my, our, his when they are already clear from context. So:

• पिता = father
• मेरे पिता = my father

If the meaning has already been established, just पिता is perfectly natural.

भी means also, too, as well.

Here it attaches to पिता:

• पिता भी = father too / father also

So the idea is that the father is included along with others.

Examples:

• मैं भी जाऊँगा। = I will go too.
• वह भी आएगी। = She will come too.

साथ means together, along, with.

In पिता भी साथ जाएँगे, it gives the sense Father will also go along / go with us / accompany us.

You may also see साथ in expressions like:

• मेरे साथ = with me
• उसके साथ = with him/her
• साथ जाना = to go along together

Here साथ works adverbially, so it does not need के or another extra word.

Because Hindi commonly uses plural verb forms for respect.

पिता is a respected family elder, so Hindi often treats him grammatically like an honorific plural. That is why you get:

• पिता जाएँगे rather than a singular casual form

This is similar to how आप takes plural-style verbs even when talking to one person.

So जाएँगे here shows respect, not literal number.

जाएँगे is the future tense of जाना (to go), in a masculine plural/honorific form.

Breakdown:

• जा- = root of to go
• -एँगे = future ending used for masculine plural / honorific subjects

So:

• वह जाएगा = he will go
• वे जाएँगे = they will go
• पिता जाएँगे = father will go (honorific)

You may also see the spelling जाएंगे in informal writing, but जाएँगे is the more standard spelling.

रहेंगे is the future form of रहना, which means to stay, remain, live.

Here, with वहाँ (there), it usually means we will stay there.

Because the subject is हम (we), the verb is in a plural form:

• मैं रहूँगा / रहूँगी = I will stay
• हम रहेंगे = we will stay

So वहाँ रहेंगे = will stay there.

It can mean either, depending on context.

रहना is a broad verb meaning:

• to stay
• to live
• to remain

In this sentence, because it is about a journey/trip, stay is the most natural English meaning:

• we will stay there

If the context were about residence, it could mean live there.

Hindi normally follows Subject–Object/Adverb–Verb order, with the verb often near the end.

This sentence is roughly:

• उस यात्रा में = in that trip
• पिता भी साथ = father also together
• जाएँगे = will go
• और = and
• हम वहाँ = we there
• रहेंगे = will stay

So Hindi tends to put important modifiers before the verb, and the verb comes last in each clause.

That is why it does not match English word-for-word order.

Yes, that is a useful literal breakdown for learning the grammar, even though it sounds unnatural in English.

A more natural English rendering would be something like:

• Father will also come along on that trip, and we will stay there.

Literal translation helps you see the Hindi structure; natural translation helps you understand the real English meaning.

Hindi does not have articles exactly like English a/an/the.

Whether something is definite or indefinite is usually understood from context, word choice, or other markers such as एक (one / a).

So:

• यात्रा can mean journey / a journey / the journey
• उस यात्रा makes it definite: that journey

Hindi simply does not need an article here.

Yes, that is a very natural interpretation.

Literally it is closer to Father will also go along, but in English that often becomes:

• Father will accompany us
• Father will come along too

The exact best translation depends on context, but the Hindi structure clearly expresses that the father is included in the trip and going together with the others.