Here are the common pronunciations:
English: "MAY-zer" (emphasis on the first syllable, with a short "a" sound like in "cat")
Polish: "MA-zoor" (emphasis on the first syllable, with a long "a" sound like in "father")
Other languages: The pronunciation may vary in other languages. It's always best to check with a native speaker if you're unsure.
Let me know if you'd like to know the pronunciation in a specific language!