Я не злюсь на тебя, но в следующий раз скажи мне заранее.

Злюсь is the 1st person singular present tense form of the verb злиться.

• злиться = to be angry, to get angry
• я злюсь = I am angry / I’m getting angry

So Я не злюсь literally means I am not angry or I’m not getting angry.

A quick mini-conjugation:

• я злюсь = I am angry
• ты злишься = you are angry
• он / она злится = he / she is angry
• мы злимся = we are angry
• вы злитесь = you are angry
• они злятся = they are angry

This verb is reflexive, which is why it ends in -ся in the dictionary form.

The verb злиться normally takes на + accusative when you say who someone is angry at.

So:

• злиться на кого? = to be angry at whom?
• на тебя = at you

That is why the sentence has:

• Я не злюсь на тебя = I’m not angry at you

Other examples:

• Я злюсь на брата. = I’m angry at my brother.
• Она злится на меня. = She’s angry at me.

For English speakers, this is something you mainly just memorize as part of the verb pattern:

• злиться на кого-то

Because after the preposition на with this meaning, Russian uses the accusative case.

The pronoun ты changes like this:

• nominative: ты = you
• accusative: тебя = you

So:

• на тебя = at you

This is the same kind of change you see in other pronouns:

• на меня = at me
• на него = at him
• на неё = at her

It can mean both in normal English.

Злиться is a common verb for being angry or annoyed. In this sentence, Я не злюсь на тебя sounds like:

• I’m not angry at you
• I’m not mad at you

Depending on tone and context, it can also suggest:

• I’m not upset with you
• I’m not holding it against you

But the most direct match is I’m not angry at you.

Но means but.

The sentence has two parts:

1. Я не злюсь на тебя = I’m not angry at you
2. в следующий раз скажи мне заранее = but next time tell me in advance

Russian normally puts a comma before но, just like English often does before but when joining two clauses.

So:

• Я не злюсь на тебя, но... = I’m not angry at you, but...

В следующий раз is a fixed expression meaning next time.

Here раз is in the accusative case because after в you can use the accusative for certain time expressions.

• раз is a masculine noun
• animate? no
• nominative singular: следующий раз
• accusative singular: следующий раз

Since it is inanimate masculine, the accusative looks the same as the nominative.

So:

• в следующий раз = next time

Very common time expressions like this are worth learning as chunks.

This is an aspect question.

• сказать = perfective, to say / tell once, to say as a completed action
• говорить = imperfective, to speak / tell / say in a general or ongoing sense

The imperative скажи is used because the speaker wants one concrete completed action in the future:

• Next time, tell me in advance.

So скажи мне заранее means:

• tell me beforehand
• make sure you let me know

If you used говори, it would sound more like a general repeated instruction such as say/tell me as a habit, and it is less natural here.

This is why скажи is the normal choice in this sentence.

Скажи is the imperative singular form of сказать.

• dictionary form: сказать
• imperative to one person: скажи
• imperative to more than one person or formal you: скажите

So:

• скажи мне заранее = tell me in advance
• скажите мне заранее = tell me in advance, please / tell me in advance, all of you

This is an irregular but very common verb, so it is best learned as a set:

• сказать
• скажу
• скажешь
• скажи

Because сказать кому? takes the dative case for the person you tell something to.

• я = I
• меня = me, in accusative/genitive contexts
• мне = to me

So:

• скажи мне = tell me

Compare:

• Он сказал мне правду. = He told me the truth.
• Скажи мне завтра. = Tell me tomorrow.

This is another useful verb pattern to memorize:

• сказать кому что
• tell someone something

Заранее means in advance, beforehand, or ahead of time.

So:

• скажи мне заранее = tell me in advance / let me know beforehand

It means the speaker wants the information before the event happens, not after or at the last minute.

Examples:

• Предупреди меня заранее. = Warn me in advance.
• Нужно купить билеты заранее. = We need to buy the tickets in advance.

Yes, the word order can change, because Russian word order is more flexible than English. The original sentence is very natural:

• ...но в следующий раз скажи мне заранее.

But you could also hear:

• ...но в следующий раз заранее скажи мне.
• ...но скажи мне заранее в следующий раз.

The original version is probably the smoothest and most neutral.

A rough sense of the focus:

• скажи мне заранее = the important point is tell me beforehand
• заранее скажи мне = slightly more emphasis on beforehand

So the word order can vary, but not every variation sounds equally natural.

It is generally neutral to mildly direct, depending on tone.

• Я не злюсь на тебя softens the sentence first.
• но в следующий раз скажи мне заранее is a direct request or instruction.

So overall it sounds like:

• not harsh
• honest
• slightly firm

If you want to sound softer, you could add пожалуйста:

• Я не злюсь на тебя, но в следующий раз скажи мне заранее, пожалуйста.

If speaking formally or to more than one person, use скажите instead of скажи:

• Я не злюсь на вас, но в следующий раз скажите мне заранее.

Yes, sometimes.

You could say:

• Я не злюсь, но в следующий раз скажи мне заранее.

That means:

• I’m not angry, but next time tell me in advance.

However, на тебя makes it clear that the speaker is saying:

• I’m not angry at you

That extra part can be important emotionally, because it reassures the other person directly.

So:

• with на тебя = more personal and explicit
• without it = shorter, but slightly less specific

Yes, Я не сержусь на тебя is also possible and natural.

Both can mean I’m not angry at you, but there is a slight difference in feel:

• злиться often sounds more like being angry, irritated, or annoyed
• сердиться often sounds a little milder or softer in many contexts

That said, in everyday speech the difference is not always huge, and both are common.

So this sentence with злюсь is perfectly normal, but a learner may also encounter:

• Я не сержусь на тебя, но в следующий раз скажи мне заранее.

Yes. There are several very useful chunks here:

• злиться на кого-то = to be angry at someone
• в следующий раз = next time
• сказать кому-то = to tell someone
• заранее = in advance

If you learn the sentence as a model, you can easily build similar ones:

• Я не обижаюсь на тебя, но в следующий раз предупреди меня заранее.
• Я не злюсь на вас, но в следующий раз скажите мне заранее.
• В следующий раз напиши мне заранее.

That makes this sentence a very good one for learning common Russian structure, not just vocabulary.