noun, adverb, noun which may take the genitive case particle 'no'
several times; multiple times
Used as a noun, adverb, or adjectival modifier to indicate that an action or event occurs more than once. Often interchangeable with 何度か, but 複数回 is slightly more formal and emphasizes the count.
This problem has occurred several times.
The same result came out in multiple tests.
Very similar in meaning, but 複数回 explicitly emphasizes 'plural/multiple' while 数回 simply means 'a few times'.
Compound of 複数 (plural, multiple) and 回 (time, occurrence).