Blocked users are unable to edit pages, move pages, and perform other actions that additional user rights would grant. Sysops or others with access to the blocking and unblocking interface may not block nor unblock others (except themselves) while blocked.
Blocked users can still view and edit their watchlists, and can still edit their own user talk page and/or send e-mails using Special:EmailUser (registered accounts only) unless specifically disallowed. Administrators and stewards can block users (unregisteredorlogged in).
Under Wikidata's blocking policy, while there are many reasons an editor may be blocked, the underlying principle is to prevent disruption to the project.
