Die Röstung bestimmt die Bohnenfarbe.

Because both nouns are feminine singular:

• die Röstung = feminine singular
• die Bohnenfarbe = feminine singular

In German, the feminine singular article is die in both the nominative and accusative cases, so the form looks the same for subject and direct object.

In a normal German statement, the subject usually comes before the verb. So here:

• Die Röstung = subject
• bestimmt = verb
• die Bohnenfarbe = direct object

So the sentence structure is:

• Subject + verb + object

Because the article forms are identical here, word order is what tells you who is doing the action.

Röstung is a noun formed from the verb rösten = to roast.

So die Röstung means something like:

• the roasting
• the roast process
• sometimes the roast

In this sentence, it refers to the roasting process or roast level as a factor that affects the beans.

Because German very often forms compound nouns by joining words together.

• Bohne = bean
• Farbe = color

Together:

• Bohnenfarbe = bean color / color of the beans

A useful rule is that the last part of a German compound is the main noun. So Bohnenfarbe is a kind of Farbe, and that is why the whole word is feminine: die Bohnenfarbe.

Also notice that Bohne becomes Bohnen- in the compound. That -n- is normal here.

Because the subject, die Röstung, is third-person singular.

The verb bestimmen is conjugated like this in the present tense:

• ich bestimme
• du bestimmst
• er/sie/es bestimmt
• wir bestimmen
• ihr bestimmt
• sie/Sie bestimmen

Since die Röstung is singular, the correct form is bestimmt.

Yes, it is in the present tense (Präsens).

Here it expresses a general fact or general truth, not something happening only right now. German uses the present tense very often for statements like this.

So the idea is:

• roasting determines bean color in general

German often uses an article where English might be more flexible.

Here, die Bohnenfarbe refers to the bean color as a specific result or characteristic. Using the article sounds natural and complete in this sentence.

German does sometimes omit articles, but usually only in certain contexts, such as:

• lists
• headlines
• some fixed expressions

In a normal full sentence like this one, die Bohnenfarbe is the expected form.

Because in German, all nouns are capitalized.

So in this sentence:

• Röstung is a noun
• Bohnenfarbe is a noun

That is why both begin with capital letters. This is one of the most noticeable spelling rules in German.

Röstung is pronounced roughly RER-stoong, but that spelling is only approximate.

A few key points:

• Rö- has the vowel ö, which does not exist exactly in standard English
• To make ö, try saying eh while rounding your lips
• Stress is on the first syllable: RÖS-tung

The u in -tung is like the vowel in put, but not exactly the same in every accent.

Yes, possibly — but the meaning changes slightly.

• die Röstung = the roasting process / the roast
• der Röstgrad = the degree of roast / roast level

If you want to talk specifically about how light or dark the roast is, der Röstgrad may be more precise. If you want to talk more generally about roasting as a process, die Röstung works well.