Dobrovolník třídí oblečení.

Dobrovolník means volunteer.

Grammar-wise, it is:

• a masculine animate noun
• in the singular
• in the nominative case here, because it is the subject of the sentence

The basic dictionary form is dobrovolník.
A feminine form would be dobrovolnice.

Třídí is the 3rd person singular present tense of the verb třídit, which means to sort or to classify.

So:

• já třídím = I sort / am sorting
• ty třídíš = you sort
• on/ona třídí = he/she sorts

Because the subject is dobrovolník (the volunteer, singular), the verb must also be singular, so třídí is the correct form.

It can mean both, depending on context.

In Czech, the present tense of an imperfective verb like třídit can describe:

• a habitual action: The volunteer sorts clothes
• an action happening right now: The volunteer is sorting clothes

Without extra context, the sentence can be understood either way.

Here oblečení is in the accusative case, because it is the direct object of the verb třídí.

The volunteer sorts what? → oblečení

The reason it does not visibly change is that oblečení is a neuter noun, and for many neuter nouns, the nominative and accusative forms are identical.

So:

• nominative: oblečení
• accusative: oblečení

They look the same, even though the grammatical role is different.

This is a very common point for English speakers.

In Czech, oblečení is usually a singular collective noun meaning:

• clothing
• clothes
• garments in a general sense

So even though English often uses the plural clothes, Czech commonly uses singular oblečení.

That means:

• třídí oblečení = sorts clothes / sorts clothing

If you want to talk about individual items, you would usually use different words, depending on what exactly you mean.

Yes, ř is one of the most famous difficult Czech sounds.

A rough guide:

• tří- sounds approximately like tree-, but with Czech ř, not normal English r
• -dí sounds like dee with a long í

About ř:

• it is a special Czech sound
• it is somewhat like a mix of r and zh/ž
• many learners cannot say it well at first, and that is normal

If you cannot pronounce ř perfectly yet, it is usually better to say something close and keep speaking than to stop completely.

Also note:

• í is a long vowel
• so in třídí, both í vowels are long

The sentence is natural as written, but Czech word order is more flexible than English word order.

This version:

• Dobrovolník třídí oblečení.

is a neutral way to say it.

Other orders are possible, for example:

• Oblečení třídí dobrovolník.
• Dobrovolník oblečení třídí.

These alternatives may change the emphasis or focus, but not the core meaning.

English relies heavily on word order for grammar. Czech relies more on case endings and agreement, so word order often expresses nuance rather than basic grammatical function.

Yes, absolutely.

Czech often omits subject pronouns and even other subjects when they are understood from context. Because třídí already tells you it is he/she/it or a formal you, the subject can be left unstated.

So:

• Třídí oblečení. = He/She is sorting clothes / He/She sorts clothes

But if you want to specify who is doing the action, you include the noun:

• Dobrovolník třídí oblečení.

Třídit is imperfective.

That means it focuses on:

• the process
• repeated action
• ongoing activity

A common perfective partner is roztřídit, which means something like:

• to sort out
• to finish sorting
• to classify completely

So:

• Dobrovolník třídí oblečení. = The volunteer is sorting clothes / sorts clothes.
• Dobrovolník roztřídí oblečení. = The volunteer will sort the clothes out / will finish sorting the clothing.

English does not mark aspect in quite the same way, so this is an important Czech pattern to notice.

Czech has no articles like English a/an and the.

So dobrovolník can mean:

• a volunteer
• the volunteer

And oblečení can mean:

• clothing
• the clothing
• some clothes
• the clothes

The exact meaning depends on context.

That is why a short Czech sentence can often be translated into English in more than one natural way.