This is the 13231st most frequent Russian word.
множественный
Multiple.
The word 'множественные' (multiple) is used as an adjective to describe 'ошибки' (errors), indicating that there are more than one.
У него обнаружили множественные ошибки в решении задачи.
He was found to have multiple errors in solving the problem.
Here, 'множественность' (multiplicity) is a noun derived from 'множественный,' indicating the concept of being numerous.
Множественность возможностей поражает своим разнообразием.
The multiplicity of opportunities amazes with its diversity.
In this case, 'множественные' modifies 'аспекты' (aspects), showing that the problem has been analyzed from various perspectives.