While viewing content within the community, if you identify inappropriate or abusive content (or members), you can flag the content as abusive. As other members also flag the content and the likelihood of its inappropriateness becomes more definitive, the content will be hidden from the site and enter the abuse workflow.
To flag content as abusive, look for the Flag as spam/abuse option in the More menu associated to the content:
Clicking this option will add your vote that the content is inappropriate for the community.
Members can also be flagged as abusive by navigating to the member's profile and clicking Flag as spam/abuse from the right sidebar: