Learn Hardcore Chinese: tā gěi wǒ de bāngzhù duì wǒ hěn zhòngyào.

First 我 (in 他给我的帮助) is the recipient of the help:
- 他给我（帮助） = He gives me help.
Second 我 (in 对我很重要) is the person affected by the importance:
- 对我很重要 = is very important to me.

So:

他给我的帮助 – “the help that he gave me”
对我 – “to/for me”
很重要 – “is very important”

You generally cannot drop either 我, because you would lose either:

who received the help, or
who finds it important.

In conversation, you could sometimes shorten the sentence if the context is very clear, but grammatically they each serve a necessary, different function here.

What does 对 mean here, and how does 对我很重要 work?

对 is a preposition that, in this structure, means something like “to / for / with regard to”.

Common pattern:

X 对 Y 很重要
= “X is very important to Y.”

In this sentence:

X = 他给我的帮助 (the help he gave me)
Y = 我 (me)

So:

他给我的帮助对我很重要。
= “The help he gave me is very important to me.”

This same pattern appears with many adjectives:

这件事对他很重要。 – This matter is very important to him.
学习汉语对你有用。 – Studying Chinese is useful to you.
健康对每个人都很重要。 – Health is very important to everyone.

Can I move 对我 to the end and say 他给我的帮助很重要对我?

No, that word order is wrong in standard Mandarin.

The usual pattern is:

[subject] + 对 + [person/thing] + 很 + 重要

So:

他给我的帮助　对我　很重要 ✅

You cannot move 对我 to the very end:

✗ 他给我的帮助很重要对我 (incorrect)

The 对 + someone phrase should come before the adjective phrase (很重要) as part of the predicate.

Why is there no 是 (“to be”) in this sentence? In English we say “is very important.”

In Chinese, adjectives can function directly as predicates; you don’t have to use 是 the way English uses “to be.”

Typical pattern:

X 很 Adj = “X is Adj.”

So:

他给我的帮助对我很重要。
Literally: “The help he gave me, to me, very important.”

You usually do not say:

✗ 他给我的帮助对我是很重要。 (awkward / over-emphatic in most contexts)

Sometimes you may see 是很重要的 in more formal or emphatic writing, e.g.:

这个问题是很重要的。 – “This issue is very important.” (with emphasis)

But the basic, neutral pattern is simply X 很重要, without 是.

Does 很 always mean “very” here, or is it sometimes just grammatical?

In sentences like this, 很 serves two roles:

Degree adverb: It can mean “very”.
Linker: It also often works as a “neutral” linker between the subject and the adjective, even when “very” isn’t strongly felt.

Traditionally:

Bare 重要 as a predicate (X 重要) sounds stiff or contrastive.
So we usually add 很 (or another degree word: 非常, 特别, etc.).

In many everyday contexts, X 很重要 is best translated as “X is important”, not necessarily strongly “very important”. Context and tone decide how strong it feels.

In your sentence, translating as “very important” is natural, but you can understand 很 partly as fulfilling a grammatical requirement of Adj as predicate.

What is the difference between 他给我的帮助对我很重要 and 他对我很重要?

They focus on different things:

他给我的帮助对我很重要。
- Subject: the help he gave me
- Meaning: “The help he gave me is very important to me.”
他对我很重要。
- Subject: he
- Meaning: “He is very important to me.”

The first sentence highlights his action / assistance.
The second sentence highlights him as a person.

Could I also say 他给我的帮助很重要 without 对我? What changes?

Yes, you can say:

他给我的帮助很重要。

This means “The help he gave me is very important,” but it doesn’t explicitly say to whom it is important. Usually, we infer it’s important to the speaker, but grammatically it’s more general.

Adding 对我:

他给我的帮助对我很重要。

makes it explicitly “important to me”, emphasizing your personal perspective.

What about 他对我的帮助很重要? Is that correct, and how is it different?

Yes, 他对我的帮助很重要 is also correct.

Structure:

他对我的帮助 – literally “his help towards me / to me”
很重要 – is very important

Nuance differences:

他给我的帮助对我很重要。
Focuses on what he gave me; emphasizes the act of giving help.
他对我的帮助很重要。
Feels a bit more like “his help to me is very important,” slightly more compact, with 对我 inside the noun phrase (他对我的帮助) rather than in the predicate.

Both are natural; the difference is subtle and often they are interchangeable in everyday speech.

Why is there no measure word before 帮助? Should it be something like 一个帮助?

帮助 here is used as an uncountable noun, similar to “help” in English.

English: “The help he gave me is very important.” (not “the one help”)
Chinese: 他给我的帮助对我很重要。

You usually don’t say 一个帮助 in this sense.
If you really want to count or quantify, you’d normally add something like:

一些帮助 – some help
很多帮助 – a lot of help

For example:

他给了我很大的帮助。 – He gave me great help / helped me a lot.