Breakdown of Cały weekend będę sprzątała kuchnię, a mój brat będzie spał.
być
to be
spać
to sleep
brat
brother
a
and / whereas (contrast)
Questions & Answers about Cały weekend będę sprzątała kuchnię, a mój brat będzie spał.
Why does the speaker say będę sprzątała instead of using the infinitive sprzątać?
Both ways are perfectly correct! In Polish, you can build the future imperfective tense using the future form of być (like będę) plus either the infinitive (sprzątać) or the l-participle. The l-participle looks exactly like the third-person past tense word. Here, the speaker is female, so she uses the feminine form sprzątała.
How does the grammar change for the brother's action?
For the brother, the sentence uses będzie (he will) plus the masculine l-participle spał. In this form of the future tense, the l-participle must always match the gender of the person or thing doing the action. If it were a sister, it would be będzie spała.
Why use a instead of i for the word and?
The word a is used because it shows a contrast between two different things happening at the same time, similar to 'while' or 'whereas' in English. You are working hard, whereas your brother is sleeping. The word i is used just to add similar things together without contrasting them.
Why does the word for kitchen change to kuchnię?
The kitchen is the direct object being cleaned, so it needs to be in the Accusative case. The basic feminine word kuchnia changes its ending from -a to -ę in this case.