אנחנו ממיינות עודפי בגדים לערימה.

Because Hebrew present-tense verb forms agree with the subject in gender and number.

• אנחנו means we, but by itself it does not show gender.
• ממיינות shows that the speakers are female plural.

So this sentence is being said by a group of women or girls.

If the group were male or mixed-gender, you would usually say:

• אנחנו ממיינים עודפי בגדים לערימה.

ממיינות is the present-tense form of למיין.

In Hebrew, the present tense can cover both:

• we sort
• we are sorting

So אנחנו ממיינות can mean either one, depending on context.

Also, Hebrew does not use a separate word for are in the present tense, so there is no extra word corresponding to English are here.

Not completely.

In the present tense, Hebrew forms like ממיינות show:

• gender: feminine
• number: plural

But they do not show person clearly by themselves. So ממיינות could mean:

• we are sorting
• you feminine plural are sorting
• they feminine plural are sorting

That is why אנחנו is useful here: it makes it clear that the subject is we.

This is a construct-state form, called smikhut in Hebrew.

The basic plural form is:

• עודפים = extras / surplus items

But when it is followed by another noun, it changes to the construct form:

• עודפי בגדים

This means something like:

• surplus clothes
• literally surpluses of clothes

So:

• עודפים = standalone form
• עודפי ... = form used before another noun

This is a very common Hebrew pattern.

Not exactly.

• עודפי בגדים is a construct phrase: surplus/excess clothes
• בגדים עודפים is a noun + adjective phrase: extra clothes

In many contexts they can be similar in meaning, but the grammar is different.

A learner should notice that:

• עודפי בגדים sounds more like a fixed or formal expression
• בגדים עודפים is more straightforwardly clothes that are extra

Because את is normally used before a definite direct object.

Here, עודפי בגדים is indefinite, so there is no את.

Compare:

• אנחנו ממיינות עודפי בגדים לערימה. = we are sorting surplus clothes into a pile
• אנחנו ממיינות את עודפי הבגדים לערימה. = we are sorting the surplus clothes into the pile

In Hebrew, definiteness matters a lot for whether את appears.

בגדים is the plural of בגד, which means garment or piece of clothing.

In normal usage, בגדים means:

• clothes
• clothing items

Hebrew often uses the plural here where English uses clothes as a plural-type noun.

So in this sentence, בגדים simply means clothes.

ל־ means to, toward, or sometimes into, depending on context.

So לערימה means something like:

• to a pile
• into a pile
• possibly to the pile, depending on context

In unpointed Hebrew spelling, לערימה can be ambiguous. The vowels would distinguish:

• לְערימה = to a pile
• לָערימה = to the pile

In everyday writing, those vowels are usually not written, so you understand it from context.

In this sentence, the natural sense is probably into a pile.

This sentence uses a very normal Hebrew word order:

• אנחנו = subject
• ממיינות = verb
• עודפי בגדים = direct object
• לערימה = destination/result phrase

So the structure is basically:

Subject + Verb + Object + Prepositional phrase

Hebrew word order can change for emphasis, but this version is neutral and natural.