This is the 9055th most frequent French word.
collectifs
Groups or collectives.
Collectifs here functions as an adjective, describing 'projets' (projects) and emphasizes their collaborative nature.
Les projets collectifs nécessitent une bonne coordination.
Collective projects require good coordination.
Collectifs is again an adjective, qualifying 'intérêts' (interests), indicating that these interests pertain to the group as a whole.
Nous avons discuté des intérêts collectifs des membres.
We discussed the collective interests of the members.
Collectifs modifies 'logements' (housing units) to denote a shared or communal aspect.