Портной кроит ткань по выкройке.

Портной is the subject of the sentence, so it is in the nominative singular.

A useful extra point: портной is a masculine noun meaning tailor, but it declines in a way that looks a bit like an adjective:

• nominative: портной
• genitive: портного
• dative: портному

So here, портной is simply the basic dictionary form because it is the one doing the action.

Кроит is the 3rd person singular present tense form of кроить.

So:

• кроить = to cut / to cut out (fabric)
• кроит = he/she cuts, is cutting

Because the subject is портной (tailor, singular), the verb is also singular: кроит.

Кроить is imperfective.

That means it is used for:

• an ongoing process
• a repeated action
• a general/habitual fact

So this sentence can mean something like:

• The tailor is cutting the fabric according to the pattern
• The tailor cuts fabric according to the pattern

depending on context.

If Russian wanted to emphasize a completed cutting action, it would usually use a perfective verb instead.

Ткань is the direct object of the verb кроит, so it is in the accusative case.

But for many inanimate feminine nouns, the accusative singular is the same as the nominative singular in form. So:

• nominative: ткань
• accusative: ткань

That is why it looks unchanged.

The ь in ткань is the soft sign. It does not add a vowel sound.

Its job is to make the final н soft. So ткань ends with a soft n sound, not a hard one.

This soft sign is also part of the noun’s normal spelling and declension pattern.

Because the preposition по here means according to or following, and in this meaning it takes the dative case.

The noun is:

• dictionary form: выкройка = pattern / sewing pattern

In the dative singular, it becomes:

• выкройке

So:

• по выкройке = according to the pattern

In this sentence, по выкройке means:

• according to the pattern
• using the pattern as a guide
• following the pattern

This is a very natural Russian way to express the idea. It does not literally mean that the tailor is physically moving on the pattern; it means the cutting is done in accordance with it.

Usually выкройка means a sewing pattern or cutting pattern—the shaped guide used to cut fabric for clothes.

So it is more specific than the very broad English word pattern. In this sentence, it clearly belongs to the vocabulary of sewing and tailoring.

Russian has no articles.

So портной can mean:

• a tailor
• the tailor

and ткань can mean:

• fabric
• the fabric
• a piece of fabric

The exact meaning depends on context, not on an article like in English.

The word order here is the most neutral one:

• Портной — subject
• кроит — verb
• ткань — object
• по выкройке — prepositional phrase

So the sentence sounds natural and straightforward.

Russian word order is more flexible than English, and you can move things around for emphasis. But this version is the best neutral starting point for a learner.

Yes, портной is normally masculine.

A feminine word you may see is портниха, though in real usage profession words can vary depending on style and context.

So in this sentence, портной tells you the tailor is grammatically masculine.

Yes.

Because кроит is an imperfective present form, it can describe either:

• what someone is doing right now
• what someone generally does

So depending on context, the sentence could mean:

• The tailor is cutting the fabric according to the pattern
• The tailor cuts the fabric according to the pattern

Russian often leaves that distinction to context.