Meningiomas are common brain growth. The vast majority of the tumours are benign. This means that they are not cancers. However, a small proportion (less than 5%) are aggressive grade III tumours.
It is quite difficult to determine if your specific meningioma is one of the rare more aggressive ones. There are some features on imaging that may provide some clues, for example if it is growing quickly, or if the tumour is invading nearby structures such as the underlying brain or the overlying bone and muscle.
None of these features are absolute. The only way to know for sure the grade of aggressiveness of a tumour, is for a sample to be sent to the pathologist for analysis.
The mainstay of treatment for meningiomas is surgical removal. If the meningioma is high grade or if it cannot all be safely removed then additional treatment in the form of radiotherapy may be considered.