Non est tibi ullus timor, si mater tecum est.

Latin very often expresses possession with sum (to be) plus a dative of the possessor.

So instead of saying you have no fear, Latin literally says something like:

No fear is to you.

Here:

• timor = fear
• est = is
• tibi = to you / for you

This is a very common Latin pattern. English usually prefers have, but Latin often prefers be in this kind of sentence.

Because tibi is the dative singular of tu, and here it marks the person who possesses something.

In other words, tibi means to you or for you, and in this construction that becomes you have in natural English.

So:

• est tibi timor = you have fear / literally fear is to you
• non est tibi ullus timor = you have no fear

This is often called the dative of possession.

Because timor is the subject of est.

In the Latin structure, the sentence is not built as you fear something. It is built as fear is to you. That means fear is the thing that is, so it must be in the nominative case.

So:

• timor = nominative singular, subject
• ullus agrees with timor, so it is also nominative singular masculine

Ullus means any or any at all.

It is especially common in negative sentences, questions, and conditions. In this sentence:

non est tibi ullus timor

it strengthens the negation:

• no fear
• not any fear at all

So ullus timor is literally any fear, but with non it comes out as no fear.

Non negates the clause, and it is very common for it to come before the verb or near the start of the sentence.

Here it negates est:

• est tibi ullus timor = you have some fear / there is fear for you
• non est tibi ullus timor = you have no fear

Latin word order is flexible, so non does not always have to be first, but this placement is perfectly natural.

With personal pronouns, cum is usually attached to the end of the pronoun instead of standing before it.

So:

• mecum = with me
• tecum = with you
• secum = with himself/herself/themselves
• nobiscum = with us
• vobiscum = with you all

So mater tecum est means mother is with you.

This is just the normal idiomatic Latin form.

Because mater is the subject of the second est.

In the clause:

si mater tecum est

the person doing the being is mater:

• mater = mother, nominative singular
• tecum = with you
• est = is

So the clause literally means if mother is with you.

Because there are really two clauses:

1. Non est tibi ullus timor
2. si mater tecum est

Each clause has its own verb:

• est = is
• est = is

Latin can sometimes omit a verb when it is understood, but here repeating est is simple and normal.

It is a simple or real condition.

• si = if
• est = is

The indicative mood is used because the sentence presents the condition as a real possibility or straightforward fact:

if your mother is with you, you have no fear

There is nothing hypothetical or contrary-to-fact here, so the ordinary indicative est is exactly what you would expect.

Latin has no definite or indefinite articles.

So:

• mater can mean mother, the mother, or a mother
• timor can mean fear, the fear, or a fear

The context tells you how to understand it. In this sentence, English naturally supplies:

• mother
• no fear

rather than forcing an article into every noun phrase.

Yes. Latin word order is much freer than English word order because the endings show the grammatical roles.

For example, these would still be understandable Latin:

• Si mater tecum est, non est tibi ullus timor.
• Non ullus timor tibi est, si mater tecum est.
• Tibi non est ullus timor, si mater tecum est.

The basic meaning stays the same, but the emphasis can shift a little depending on the order.

Yes. Ullus is one of those words that often appears where English uses any.

So in a negative sentence:

• non ... ullus = no ... / not any ...

Compare the idea in English:

• I have no fear
• I do not have any fear

Latin often uses ullus in exactly that kind of environment. So non est tibi ullus timor is very natural Latin for you have no fear.