In general, German is pronounced "as it is written".
I.e. the same letter or letter combination is (almost) always pronounced the same.

How to explain pronounciation in a language, where letters/letter combinations have many different ways of pronounciation?

Some examples:

"tough", "though", "thought", "trough", "thought", "thorough" all have the combination "ough" - but in each word it is pronounced differently;

or "read" vs. "read" - depending on whether it's present or past time;

or "north" vs. "word";

cu, MudGuard a/k/a Andreas (from Munich/Germany)

or "either" - depending on British/American/Australian English;

or ...