Moja siostra bierze grabie, a ja biorę łopatę i pracujemy od rana do obiadu.

Because siostra is a feminine noun, and the possessive adjective my has to agree with it in gender, number, and case.

• mój = masculine singular
• moja = feminine singular
• moje = neuter singular

So:

• mój brat = my brother
• moja siostra = my sister
• moje dziecko = my child

Here siostra is feminine, so moja is the correct form.

Both forms come from the same verb: brać = to take. This verb has an irregular-looking present tense stem change, so the forms are not built in a fully predictable way from the infinitive.

Present tense of brać:

• biorę = I take
• bierzesz = you take
• bierze = he/she/it takes
• bierzemy = we take
• bierzecie = you all take
• biorą = they take

So:

• moja siostra bierze = my sister takes
• ja biorę = I take

This is just one of those verbs whose present tense you need to learn as a pattern.

Yes, grabie is grammatically plural. It is a good example of a noun that is normally used only in the plural, even when it refers to a single tool.

So Polish treats grabie a bit like English words such as scissors or trousers:

• English: These scissors are new
• Polish: Te grabie są nowe

In the sentence:

• moja siostra bierze grabie

the verb is singular because the subject is moja siostra, not grabie.
Grabie is the object.

Also, the accusative form here looks the same as the nominative, which is common with some plural nouns.

Because łopata is the dictionary form, but after biorę the noun is the direct object, so it goes into the accusative case.

For a feminine noun ending in -a, the accusative singular usually ends in -ę:

• łopata = shovel, spade
• biorę łopatę = I take a shovel / spade

More examples:

• mam książkę from książka
• widzę kobietę from kobieta

So łopatę is the normal accusative singular form.

In Polish, a often connects two clauses when there is a contrast, a shift of topic, or a comparison between two people or actions. It does not always mean strong opposition like English but; very often it means something like and as for... or while....

So here:

• Moja siostra bierze grabie, a ja biorę łopatę

has the sense of:

• My sister takes the rake, and I take the shovel
• or more literally, My sister takes the rake, while I take the shovel

Using i ja here would sound less natural, because the sentence is setting up a contrast between what she takes and what I take.

Because the subject of pracujemy is really my sister and I together.

Even though Polish does not repeat the full subject, the meaning is:

• Moja siostra bierze grabie, a ja biorę łopatę i pracujemy...
• effectively: My sister takes the rake, I take the shovel, and we work...

When the subject includes I plus someone else, Polish uses the first person plural:

• ja + on/ona = my
• I + he/she = we

So pracujemy = we work is exactly what Polish grammar requires.

Polish often leaves subject pronouns out because the verb ending already shows the person and number.

• biorę already means I take
• pracujemy already means we work

So the pronouns are often unnecessary.

Here ja is included because it helps create the contrast with moja siostra:

• moja siostra ... a ja ...

That explicit ja is useful. But after that, Polish does not need to add my before pracujemy, because the ending -my already tells you it means we.

The prepositions od and do normally require the genitive case.

That is why you get:

• do obiadu, not do obiad

Here:

• obiad = nominative
• obiadu = genitive

The phrase od rana is a very common fixed expression meaning from the morning / since early morning, and the whole phrase od rana do obiadu means a span of time from morning until the midday meal.

So this part is best learned as a useful time expression:

• od rana do obiadu
• od rana do wieczora
• od poniedziałku do piątku

This is a very common question, because obiad does not match perfectly with a single English meal word.

In modern Polish, obiad usually means the main cooked meal of the day, often eaten around midday or in the early afternoon. In many contexts, that is closer to lunch; in some families it may feel closer to dinner.

So in this sentence, do obiadu is best understood as:

• until lunch
• or until the main midday meal

It usually does not mean late-evening dinner in the English sense.

Brać is the imperfective verb, while wziąć is its perfective partner.

Very roughly:

• brać focuses on the action as ongoing, repeated, or part of a situation
• wziąć focuses on taking something as a completed act

In this sentence, the imperfective forms bierze and biorę fit naturally because the sentence is setting the scene: she takes one tool, I take another, and then we work. It feels descriptive and connected to the ongoing activity.

If you used wziąć, the focus would be more on the completed moment of picking something up.

Because Polish verbs already contain that information in their endings.

• pracuję = I work
• pracujesz = you work
• pracuje = he/she/it works
• pracujemy = we work

So once Polish uses pracujemy, the subject we is already built into the verb.

In full, you could say i my pracujemy, but that would usually sound unnecessary unless you wanted special emphasis.

Yes. Polish word order is more flexible than English word order, because endings show grammatical relationships more clearly.

The original sentence is natural and clear, but some parts could be rearranged for emphasis. For example, od rana do obiadu could move:

• Pracujemy od rana do obiadu
• Od rana do obiadu pracujemy

Both are correct, but the second one emphasizes the time span more strongly.

Still, the original version is a very normal, neutral way to say it.