der Krach
noise / crash
A loud, sudden, and often unpleasant noise caused by an impact, breakage, or explosion.
Ich bin durch einen lauten Krach aus der Küche aufgewacht.
I woke up because of a loud crash from the kitchen.

noise / argument / crash
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noise / crash
A loud, sudden, and often unpleasant noise caused by an impact, breakage, or explosion.
Ich bin durch einen lauten Krach aus der Küche aufgewacht.
I woke up because of a loud crash from the kitchen.

To understand the meaning of 'Krach' (noise / argument / crash), pay attention to the context. Is it about a sudden noise, an argument between people, or the financial world? The accompanying words give the crucial clue.
Der Krach kam von einem umfallenden Stuhl.
The crash came from a chair falling over.
In connection with noise, the phrase 'Krach machen' (to make a loud noise) or 'Krach schlagen' (to protest noisily / make a fuss) is often used.
Hört bitte auf, so einen Krach zu machen!
Please stop making such a racket!
When 'Krach' (argument / row) means an argument, the construction 'Krach mit jemandem haben' (to have an argument with someone) is often used. The preposition 'mit' introduces the person one is arguing with.
Sie hat ständig Krach mit ihren Eltern.
She is constantly having arguments with her parents.
The meaning 'Streit' (argument) is especially common in colloquial language. In more formal contexts, words like 'Streit' (dispute / argument) or 'Auseinandersetzung' (conflict / confrontation) would be used instead.
Wegen des Geldes gab es mal wieder Krach in der Familie.
There was yet another row in the family because of the money.
In a financial context, 'Krach' (crash) is almost always part of the fixed term 'der Börsenkrach' (the stock market crash). The word is rarely used on its own with this meaning.
Der Börsenkrach von 1929 hatte weltweite Folgen.
The stock market crash of 1929 had worldwide consequences.
quiet / calm
'die Ruhe' and 'der Krach' are opposites when talking about sounds. 'Ruhe' means that there are no disturbing noises. 'Krach' is a loud, often unpleasant noise, for example when something falls down or breaks. So 'Ruhe' fits quiet places or moments, while 'Krach' fits sudden noise.

Am Abend hörte Herr Becker einen lauten Krach im Treppenhaus.
In the evening, Mr. Becker heard a loud crash in the stairwell.
In der Praxis herrscht Ruhe, damit die Patienten sich entspannen können.
There is quiet in the clinic so that the patients can relax.