An indivudual or organization that financially suports a project. In the financing of film projects, sponsors are almost indispensable. In return, company logos might appear on movie posters and film titles increasging awareness of the entity. The so-called "sponsorship" does not only mean the provision of funds. Jobs at film premieres e.g. well-known car companies offer their cars to chauffeur the stars, so the automaker promotes its models.
Another method of sponsorship is so-called product placement: somewhere in the action or setting of a movie a car or other prop appears on screen and is perhaps used by the actor(s) as a highly visible advertisemt for a car brand for example. A famous example is the James Bond films, which always showcase a new car. Smaller items like cigarette boxes, clocks, advertising itself, etc is used as Product Placement.