Он решил избавиться от старых вещей.

Решил is the past tense masculine singular form of решить = to decide.

It matches он because Russian past tense agrees with the subject in gender and number:

• он решил = he decided
• она решила = she decided
• они решили = they decided

So in this sentence, он решил literally means he decided.

After решить in the sense of to decide to do something, Russian normally uses an infinitive:

• решил уйти = decided to leave
• решил купить = decided to buy
• решил избавиться = decided to get rid of

So the structure is:

он решил + infinitive

That is the standard way to say he decided to ...

Избавиться means to get rid of or to free oneself from something.

It is related to избавить, but they are not used the same way:

• избавить кого-то от чего-то = to rid someone of something
• избавиться от чего-то = to get rid of something oneself

So:

• Он избавил друга от проблем = He freed his friend from problems
• Он избавился от проблем = He got rid of his problems

In your sentence, избавиться is the correct verb because the subject is the one getting rid of the things.

The -ся ending is a reflexive marker. Very often, it changes a verb so that the action somehow returns to the subject or becomes self-directed.

Here it helps create the meaning:

• избавить = to rid someone/something
• избавиться = to get rid of something oneself

So -ся is an important part of the verb. You cannot remove it here without changing the meaning and grammar.

Because избавиться normally goes with от.

The pattern is:

избавиться от + genitive

This is just the standard construction Russian uses for to get rid of.

Examples:

• избавиться от страха = to get rid of fear
• избавиться от мусора = to get rid of trash
• избавиться от старых вещей = to get rid of old things

So от is required by the verb.

Because от requires the genitive case, and both words must match that.

Here:

• старых = genitive plural of старые
• вещей = genitive plural of вещи

So:

• dictionary form: старые вещи = old things
• after от: от старых вещей

This is one of the most important things to notice in the sentence: the verb phrase избавиться от triggers the genitive.

Because the noun is in the genitive plural, not the nominative or accusative plural.

The basic forms are:

• вещь = thing
• вещи = things / of a thing, depending on case
• вещей = of things

In this sentence, the meaning is not just old things in a neutral dictionary form. It is specifically from old things / of old things after от, so Russian uses вещей.

Избавиться is perfective.

Its imperfective partner is избавляться.

The difference is roughly:

• избавляться = to be getting rid of, to get rid of in a general or repeated/process sense
• избавиться = to get rid of successfully, as a completed action

After решил, Russian often uses a perfective infinitive when talking about a single intended result:

• Он решил избавиться от старых вещей = He decided to get rid of the old things

That sounds natural because the focus is on accomplishing the action, not on the ongoing process.

Yes. Russian word order is more flexible than English word order.

The neutral order here is:

Он решил избавиться от старых вещей.

But you could also say:

• От старых вещей он решил избавиться.
• Избавиться от старых вещей он решил давно.

These versions shift the emphasis or topic, but the core meaning stays similar.

So the original sentence is the most straightforward, neutral version.

The standard stress is:

Он реши́л изба́виться от ста́рых веще́й.

A few useful notes:

• реши́л — stress on the last syllable
• изба́виться — stress on ба
• ста́рых — stress on the first syllable
• веще́й — stress on the last syllable

Stress matters in Russian, so it is worth learning these together with the words.

Russian does not have articles like English the or a/an.

So старых вещей can mean things like:

• old things
• the old things
• some old things

The exact interpretation depends on context.

In this sentence, English may translate it as old things, his old things, or the old things, depending on the situation, but Russian does not need an article to express that.

Yes. Вещи often means things, belongings, or items. In a sentence like this, it usually suggests physical possessions or household items rather than abstract ideas.

So старые вещи often sounds like:

• old belongings
• old stuff
• old clothes/items/things

The exact nuance depends on context, but it usually refers to possessions someone wants to clear out.