While learning Marathi it is important to understand the customs or traditions of the Marathi community which get reflected in language. One important aspect to learn is how elders are addressed in Marathi.

In Marathi, plurals are used to indicate respect. This is called आदरार्थी बहुवचन (AdarArthI bahuvachan )

e.g. If you are talking about the prime minister of you are country. In English, you will say,  “He is Prime Minister. He is speaking”.
As seen before in Marathi, “He” in English is तो (to) in Marathi. So In Marathi, literal translation will be : तो पंतप्रधान आहे. तो बोलत आहे ( to paMtapradhAn Ahe. to bolat Ahe )
But because you are talking about P.M. and you will want to say these sentences with respect, so actually you will use the plural of तो (to) which is ते(te). And the sentence will be formed accordingly.
So Marathi sentence will be ते पंतप्रधान आहेत. ते बोलत आहेत ( te paMtapradhAn Ahet. te bolat Ahet ).
Which if translated literally in English, it will be “They are Prime Minister. They are speaking”. Which sounds odd in English. But in Marathi, it is the natural and correct way. And it should be followed when you are talking with an elder person or with anyone who you want to give respect to.

Similarly, if you are talking about lady
She is good -> ती चांगली आहे ( tI chAMgalI Ahe )
When saying with respect; plural of is ती(tI) is त्या(tyA). So sentence will be
त्या चांगल्या आहेत( tyA chAMgalyA Ahet ).

Similarly “How are you” is translated as
तू कसा आहेस ( tU kasA Ahes )
Plural of तू (tU) is तुम्ही( tumhI). So question with respect will be asked as
तुम्ही कसे आहात ( tumhI kase AhAt )

In old-time few learned persons or rich person, used to address themselves with respect. So they used आम्ही ( AmhI) which is “we” in English while talking about themselves.
I am coming -> मी येतो आहे ( mI yeto Ahe )
Giving oneself respect they used to say आम्ही येत आहोत ( AmhI yet Ahot )
In editorials of Marathi newspaper, you will find editor calling himself आम्ही (AmhI)
But nowadays in day-to-day communication, nobody calls himself आम्ही ( AmhI) as it looks like boasting.

I have listed pairs here just for reference:-

मी -आम्ही mI -AmhI
तू -तुम्ही ( tU -tumhI )
तो – ते ( to – te )
ती -त्या ( tI -tyA )
ते -ती ( te -tI )

Even if sentences do not have pronouns; it should be formed with a plural way to indicate respect.
Shivaji Maharaj was great
Literal translation -> शिवाजी महाराज महान होता ( shivAjI mahArAj mahAn hotA)
Correct way with respect ->
शिवाजी महाराज महान होते ( shivAjI mahArAj mahAn hote)

Kaushik is my teacher Literal translation -> कौशिक माझा शिक्षक आहे ( kaushik mAjhA shikshak Ahe )
Correct way with respect -> कौशिक माझे शिक्षक आहेत ( kaushik mAjhe shikshak Ahet )

Note that, we do not use the plural of the main noun. The plural form of the only pronoun, adjective, the verb is used.
Your mother is good (with respect) -> तुझ्या आई चांगल्या आहेत (tujhyA AI chAMgalyA Ahet).
We used आई(AI) and not it’s plural i.e आया (AyA)

Another example,
She is my husband’s sister -> त्या माझ्या नणंद आहेत (tyA mAjhyA naNaMd Ahet). We will not use “नणंदा”(naNaMdA) which is plural of नणंद (naNaMd)

But when you use a preposition with a noun, we use the plural.
e.g. To mother (literal translation) -> आईला (AIlA)
To mother (with respect) ->आईंना (AIMnA)

For teacher (literal translation) -> शिक्षकासाठी (shikShakAsAThI)
For teacher (with respect) ->शिक्षकांसाठी (shikShakAMsAThI )

I have thoroughly discussed preposition in a later chapter. So revisit this part after you are clear with that concept.

Using आपण (ApaN) instead of तुम्ही(tumhI)

When speaking very formally or in very formal written communication instead of तुम्ही(tumhI) we use आपण (ApaN). Rest of the sentence structure remains the same.
How are you ->
(With respect) तुम्ही कसे आहात ( tumhI kase AhAt )
(Very formal communication ) -> आपण कसे आहात ( ApaNkase AhAt )

You are doing work ->
(With respect) तुम्ही काम करत आहात ( tumhI kAm karat Ahat )
(Very formal communication ) -> आपण काम करत आहात ( ApaN kAm karat Ahat )

What do you want ->
(With respect) तुम्हाला काय पाहिजे? ( tumhAlA kAy pAhije)
(Very formal communication ) -> आपल्याला काय पाहिजे? ( ApalyAlA kAy pAhije )

Listen examples online