Je râpe du fromage pendant que Paul chauffe la soupe.

In French, you usually need an article before a noun. Here, du fromage is the partitive article, which often means some cheese or cheese in an unspecified amount.

So:

• Je râpe du fromage = I’m grating some cheese / cheese

English often drops some, but French usually does not.

Not really, even though du is historically the same form as de + le.

In this sentence, du is functioning as a partitive article, so it does not mean of the word-for-word. It’s better to understand du fromage as some cheese.

So avoid translating it too literally.

La soupe means the soup. It refers to a specific soup that Paul is heating.

• Paul chauffe la soupe = Paul is heating the soup

If you said de la soupe, that would usually mean some soup, focusing more on an unspecified quantity rather than a specific soup already understood in the situation.

French often uses the simple present where English uses the present progressive.

So:

• Je râpe can mean I grate or I am grating
• Paul chauffe can mean Paul heats or Paul is heating

The context tells you that these actions are happening now.

If you want to strongly emphasize that something is in progress, French can use:

• Je suis en train de râper du fromage.

But the simple present is the most natural basic version here.

Pendant que means while or during the time that. It introduces a clause with its own subject and verb.

Here:

• pendant que Paul chauffe la soupe = while Paul is heating the soup

A useful comparison:

• pendant
  • noun
    
    • pendant le repas = during the meal
• pendant que
  • full clause
    
    • pendant que Paul chauffe la soupe = while Paul heats the soup

Yes, often you can.

• pendant que = while, during the time that
• tandis que = while, but often a little more formal or slightly more contrastive

So this would also work:

• Je râpe du fromage tandis que Paul chauffe la soupe.

In this sentence, pendant que sounds very natural and neutral.

Because je only contracts to j’ before a vowel sound or a mute h.

For example:

• j’aime
• j’habite

But râpe begins with a consonant sound, so you keep je:

• je râpe

They are both present tense forms of regular -er verbs:

• râper = to grate
• chauffer = to heat, warm up

In the sentence:

• râpe = 1st person singular: je râpe
• chauffe = 3rd person singular: Paul chauffe

So the structure is very straightforward:

• subject + present tense verb

Râpe is pronounced roughly like rahp.

The circumflex in â is mostly a spelling marker. In modern French, it often does not dramatically change pronunciation, although depending on accent it may slightly affect the vowel quality.

For learners, the main thing is:

• learn the word as râpe
• pronounce it as one syllable, roughly rahp

Also, râpe is pronounced the same whether it is:

• the verb form je râpe
• the noun une râpe = a grater

You would say:

• Je ne râpe pas de fromage pendant que Paul chauffe la soupe.

A very important rule appears here: after negation, du / de la / des usually become de.

So:

• Je râpe du fromage.
• Je ne râpe pas de fromage.

That is a very common pattern in French.