Він відмовився від посади.

Відмовився is the past tense, masculine singular form of the verb відмовитися.

So in this sentence:

• він = he
• відмовився = refused / declined / gave up (past, masculine)
• від посади = the position / the post

Because the subject is він, the verb takes the masculine past form.

Compare:

• Він відмовився = He refused
• Вона відмовилася = She refused
• Вони відмовилися = They refused

The -ся ending is the Ukrainian reflexive marker. In some verbs it has a clearly reflexive meaning, but very often it is just part of the verb’s normal dictionary form.

Here, the full verb is відмовитися, and the common pattern is:

відмовитися від + genitive

This means to refuse, to decline, to give up, or sometimes to renounce something.

So you should learn відмовитися від as a whole pattern, not just відмовити plus an extra ending.

Because the preposition від requires the genitive case.

The basic noun is:

• посада = position / post / office

But after від, it changes to the genitive singular:

• посади

So:

• від посади = from the position / of the position, depending on context

This is part of the standard structure:

• відмовитися від роботи = to give up the job
• відмовитися від ідеї = to give up the idea
• відмовитися від посади = to give up / decline the position

It can depend on context.

Most literally, відмовитися від посади means to refuse or decline a position/post. For example, if someone is offered a job or office and says no, this phrase fits very naturally.

In some contexts, it can also mean to give up a post or step down from it.

If you want a very clear idea of resigned from office / left the post, Ukrainian often uses other expressions, such as:

• пішов з посади = left the post / stepped down
• звільнився з посади = resigned from the post
• подав у відставку = submitted his resignation / resigned
• склав повноваження = stepped down / laid down his powers

So відмовився від посади is understandable, but its exact nuance depends on whether the position was being offered or already held.

Because Ukrainian has no articles. There is no direct equivalent of a or the.

So посади can mean:

• a position
• the position
• sometimes even the post or the office

The exact meaning comes from context.

That is very normal in Ukrainian. English needs articles, but Ukrainian usually does not.

Yes, very often.

Ukrainian frequently drops subject pronouns when the meaning is clear from context. So:

• Він відмовився від посади.
• Відмовився від посади.

Both can work.

Why keep він?

• to make the subject explicit
• to add contrast or emphasis
• to avoid ambiguity in context

Also, even without він, відмовився already tells you the subject is masculine singular in the past.

Відмовитися is perfective.

That means it usually refers to a completed single action: he refused, he made the decision, it happened.

The imperfective partner is відмовлятися.

Compare:

• Він відмовився від посади. = He refused/gave up the position.
  (a completed action)

• Він відмовлявся від посади. = He was refusing the position / kept refusing the position.
  (process, repeated action, or background description)

For learners, this is a useful pair to remember:

• відмовлятися = imperfective
• відмовитися = perfective

Yes. Ukrainian word order is fairly flexible because the case endings show grammatical relationships.

The sentence you have is a neutral, natural order:

• Він відмовився від посади.

But you could also hear:

• Від посади він відмовився.
• Він від посади відмовився.

These alternatives change the emphasis a bit:

• starting with Від посади can emphasize the position
• keeping він first is more neutral

So the original version is a very normal default sentence, but it is not the only possible order.