Anything can be a project, in basically any industry. Marketing or advertising campaigns, development of new products... A relative works for a huge corp that renovates buildings after flooding and there are tons of different teams of people that need to be coordinated among and between to complete that kind of job. Think of a hospital that is full of mold after a flood and the kind of rigorous restoration needed to bring it back into a usable state.

Another whole category are government contracts: there are engineering and architecture firms that employ thousands of people with hundreds of contracts, having teams of dozens of people making plans for all kinds of shit for the feds, states, and cities (transportation, infrastructure, land use, conservation... You name it). Then all of those plans have things that need to get implemented, usually by construction crews with their own PMs.

Construction projects for one example

The other comments give good examples. A project is essentially something that a group wants to accomplish. It can be work related, but it can be in activist, volunteer, or other groups as well.

Examples: fulfilling a scientific grant to discover or develop a new technology, development of an app, construction of a new grocery store, running a clinical trial, environmental restoration of a damaged forest, putting together a labor organization workshop...really any project that is big enough that it needs to be broken down into smaller parts and would be difficult for the group doing the work to accomplish without someone taking on a role that specifically monitors the larger picture.