Коли я ріжу хліб ножем, я іноді ріжу палець, тому вдома завжди є пластир.

Here коли means when / whenever in the sense of a repeated situation.

In English, when I cut bread with a knife can mean every time I do that. Ukrainian uses коли the same way:

• Коли я ріжу хліб ножем... = When/Whenever I cut bread with a knife...

If the meaning were more conditional, like if I cut bread, Ukrainian would more likely use якщо.

Ukrainian often uses the present tense for habitual or repeated actions, just like English does.

So:

• я ріжу хліб = I cut bread / I am cutting bread, depending on context
• я іноді ріжу палець = I sometimes cut my finger

The present tense here describes something that happens from time to time, not necessarily at this exact moment.

Ріжу is the 1st person singular present tense form of різати or різати / різатися-related stem meaning to cut.

So:

• я ріжу = I cut
• ти ріжеш = you cut
• він/вона ріже = he/she cuts

This is an imperfective verb form, which fits repeated or ongoing actions well.

Because хліб is the direct object, it is in the accusative case. For many masculine inanimate nouns, the accusative singular looks exactly like the nominative singular.

So:

• nominative: хліб
• accusative: хліб

That is why you do not see a different ending here.

Because ножем is the instrumental case of ніж.

The instrumental case is commonly used for the tool or means by which something is done:

• ріжу ножем = I cut with a knife
• пишу ручкою = I write with a pen
• їду автобусом = I go by bus

So ножем answers the question with what?

Here палець is also a direct object, so it is in the accusative case. But палець is a masculine inanimate noun grammatically, so its accusative singular is the same as its nominative singular:

• nominative: палець
• accusative: палець

Even though a finger is part of a person, grammatically the noun is treated as inanimate.

Because Ukrainian often omits possessive words like my when the ownership is obvious, especially with body parts and personal items.

So:

• я ріжу палець naturally means I cut my finger
• він миє руки = he washes his hands
• вона заплющила очі = she closed her eyes

You can add мій for emphasis or contrast, but it is usually unnecessary here.

Yes, іноді can move because Ukrainian word order is fairly flexible.

In this sentence:

• я іноді ріжу палець

means I sometimes cut my finger.

You could also hear:

• іноді я ріжу палець
• я ріжу палець іноді

But the original placement is very natural and neutral. Moving іноді changes emphasis more than basic meaning.

Here тому means therefore / so / that’s why.

It connects the second part of the sentence to the first as a result:

• ..., тому вдома завжди є пластир.
• ..., so there is always a bandage/band-aid at home.

A useful distinction:

• тому = therefore / that’s why
• бо = because

So тому introduces the consequence, not the reason.

Вдома is an adverb meaning at home.

That makes it the most natural choice here:

• вдома = at home

By contrast:

• у домі literally means in the house/building

So if you want the general idea of at home, use вдома. It is very common in everyday Ukrainian.

That is a very common question. Ukrainian often omits the present tense of бути in sentences like:

• Я студент. = I am a student.

But in existential sentences meaning there is / there are, є is normally used:

• У мене є книга. = I have a book.
• Вдома є пластир. = There is a bandage/band-aid at home.

So here є does not simply mean is. It marks existence or availability: there is / there exists.

The singular here is natural because it refers to the item in a general, practical sense: there is always a bandage/band-aid available.

English does something similar:

• There’s always a band-aid at home.

It does not necessarily mean exactly one bandage. It just means the household keeps that item on hand.

Also, пластир in Ukrainian often means an adhesive bandage / sticking plaster, not a large medical bandage in general.

There are two commas because the sentence has separate clauses.

• Коли я ріжу хліб ножем, ...
  The comma separates the subordinate clause introduced by коли from the main clause.

• ..., я іноді ріжу палець, тому вдома завжди є пластир.
  The second comma separates the result clause introduced by тому.

So the punctuation helps show the structure:

1. When I cut bread with a knife
2. I sometimes cut my finger
3. therefore there is always a bandage at home

Yes. Ріжу is imperfective, which is appropriate for:

• repeated actions
• habitual actions
• ongoing processes

That fits both parts of the sentence:

• Коли я ріжу хліб... = a repeated or ongoing activity
• я іноді ріжу палець = something that happens from time to time

A perfective verb would suggest a completed single event, which would not fit this general habit-based statement as well.

Yes, Ukrainian allows a lot of flexibility in word order. For example:

• Коли я ріжу хліб ножем, я іноді ріжу палець...
• Я іноді ріжу палець, коли ріжу хліб ножем...
• Тому вдома завжди є пластир could also be placed earlier for emphasis in a different context.

The original order is natural because it presents:

1. the situation
2. the problem
3. the consequence

That makes it easy to follow.