Nisalimie familia.

No. Here ni- does not mean I as the subject. It is an object marker meaning me.

So the idea is:

• understood subject: you
• ni-: me
• salimie: greet

So the sentence is literally something like [You] greet the family for me.

Yes. The subject you is understood but not spoken.

That is very normal in Swahili commands and requests. So Nisalimie familia is addressed to one person, even though the word you does not appear.

Because this is a request/command form with an object marker attached.

In Swahili, when a command includes an object marker like ni- for me, the verb usually appears in the subjunctive form, which often ends in -e.

Compare:

• Salimia familia. = Greet the family.
• Nisalimie familia. = Greet the family for me.

So salimie is the expected form here.

The key verb here is salimia, meaning greet or send greetings to.

Then:

• salimia → basic dictionary-style form
• salimie → subjunctive/request form
• nisalimie → greet for me / greet on my behalf

So nisalimie is built from salimia plus the object marker ni-.

Because Swahili does not need a separate word like to here.

The verb salimia directly takes the person or group being greeted as its object. So familia comes straight after the verb:

• salimia familia = greet the family

English says say hello to the family, but Swahili expresses that idea more directly.

Swahili does not use articles like English a/an and the.

So familia can mean:

• family
• a family
• the family

The exact meaning depends on context. In this sentence, it is usually understood as the family.

The sentence does not say explicitly.

By itself, familia just means family / the family. If you want to be specific, you can add a possessive:

• familia yangu = my family
• familia yako = your family
• familia yake = his/her family

So if you want Greet my family for me, you could say Nisalimie familia yangu.

You would say:

• Nisalimieni familia.

So the difference is:

• Nisalimie familia. = said to one person
• Nisalimieni familia. = said to more than one person

A simple way is to add tafadhali, meaning please:

• Tafadhali, nisalimie familia.

Even without tafadhali, the sentence is already a normal and natural request. Adding tafadhali just makes it softer and more explicitly polite.