Bibi anaimba wimbo ili kutuliza mtoto.

anaimba can be broken down as:

• a- = he/she
• -na- = present or ongoing action
• imba = sing

So anaimba means he/she is singing or he/she sings, depending on context.

It can mean either one. The -na- tense in Swahili often covers both:

• she is singing
• she sings

Context tells you which is more natural in English. In this sentence, is singing is usually the best fit.

ili introduces a purpose, so it means something like:

• so that
• in order to

It tells you why the grandmother is singing.

kutuliza is the infinitive form, meaning to calm or to soothe.

• ku- = to
• tuliza = calm/soothe

In this sentence, the infinitive is used after ili to express purpose: in order to calm.

By contrast, tuliza by itself is often an imperative, meaning calm! or soothe!

tuliza means calm, soothe, or more literally make calm. It is related to tulia, which means be calm or become calm.

So:

• tulia = become calm
• tuliza = make someone calm

That is why kutuliza mtoto means to calm the child or to soothe the child.

mtoto is singular and means child. Its plural is watoto, meaning children.

So here mtoto refers to one child.

The sentence follows a very common Swahili order:

• Bibi = subject
• anaimba = verb
• wimbo = object
• ili kutuliza mtoto = purpose phrase

So the structure is basically:

Subject + Verb + Object + Purpose

That is quite similar to English word order.

Because tuliza is a transitive verb: it can take a direct object directly.

So:

• kutuliza mtoto = to calm the child

You do not need a preposition there. This works much like English calm the child, where the child is also a direct object.