This is the 4567th most frequent French word.
mensuel
Monthly.
Here, 'mensuel' is used as an adjective describing the periodical publishing schedule of the magazine.
Le magazine est publié de manière mensuelle.
The magazine is published monthly.
In this sentence, 'mensuel' is again an adjective, qualifying the noun 'salaire' to indicate its recurring timing.
Je viens de recevoir mon salaire mensuel.
I just received my monthly salary.
'Mensuel' in this context details the frequency of the meeting, used as an adjective modifying 'réunion'.