Tafadhali usile embe hili kwa sababu bado ni bichi.

Tafadhali means please.

It adds politeness, but it does not change the basic grammar of the sentence. The command is still usile = don’t eat. So tafadhali usile... means please don’t eat...

You can think of it as a polite softener at the beginning of the sentence.

Usile is the form used to tell one person don’t eat.

In Swahili, negative commands are usually built into the verb itself rather than using a separate word like English don’t. So instead of something like don’t + eat, Swahili uses one verb form: usile.

A useful comparison is:

kula = eat! / to eat
usile = don’t eat!

If you were speaking to more than one person, you would say msile.

The ku- in kula is the infinitive marker, like to in English to eat.

So:

kula = to eat

But when the verb is conjugated, Swahili usually works with the verb stem rather than keeping the infinitive ku-. The stem here is -la.

So usile is built from the verb stem -la, not from the full infinitive kula.

Swahili does not usually use articles the way English does.

So embe can mean a mango or the mango, depending on context. In this sentence, hili makes it specific, so embe hili means this mango.

English requires articles very often, but Swahili usually does not.

In Swahili, demonstratives like this usually come after the noun.

So the normal order is:

embe hili = this mango
kitabu hiki = this book
mtoto huyu = this child

This is different from English, where this comes before the noun.

Hili is the form of this that agrees with the noun class of embe.

Embe is a singular noun in class 5, and class 5 uses hili for this.

That is why you get:

embe hili = this mango

If it were plural, the noun would be maembe, and the demonstrative would change:

maembe haya = these mangoes

So the demonstrative changes to match the noun class.

Kwa sababu means because.

It introduces the reason for what was just said:

Tafadhali usile embe hili = Please don’t eat this mango
kwa sababu bado ni bichi = because it is still unripe

Literally, it is something like for the reason or because of the reason, but in normal English translation you should just think because.

Bado means still here.

So:

bado ni bichi = it is still unripe

In other contexts, bado can also be understood as yet, depending on the sentence. But in this example, still is the natural meaning.

Ni is the copula, the word that works like is / are in English.

So:

ni bichi = is unripe

That means:

bado ni bichi = is still unripe

Swahili often uses ni to link a subject with a noun or adjective-like description.

Here bichi means unripe.

With fruit, bichi usually means not ripe yet. In other contexts, it can also mean raw, green, or uncooked, depending on what is being described.

As for its form, Swahili adjectives often change to agree with noun class, but some forms are quite short or appear without much extra marking in the singular. With embe, bichi is the natural form.

If you make it plural, you can see the agreement more clearly:

embe hili ni bichi = this mango is unripe
maembe haya ni mabichi = these mangoes are unripe

So bichi is the correct singular form here, and mabichi is the plural form with maembe.

You change the command form and/or the noun phrase, depending on what is plural.

If you are speaking to several people but still talking about one mango:

Tafadhali msile embe hili kwa sababu bado ni bichi.
= Please don’t eat this mango because it is still unripe.

If you are speaking to one person about several mangoes:

Tafadhali usile maembe haya kwa sababu bado ni mabichi.
= Please don’t eat these mangoes because they are still unripe.

If both are plural:

Tafadhali msile maembe haya kwa sababu bado ni mabichi.
= Please don’t eat these mangoes because they are still unripe.