If you describe something such as a task or an activity as, for example, a difficult proposition or an attractive proposition, you mean that it is difficult or pleasant to do.

A proposition is a statement or an idea that people can consider or discuss to decide whether it is true.

A proposition is a question or statement about an issue of public policy that appears on a voting paper so that people can vote for or against it.

A proposition is an offer or a suggestion that someone makes to you, usually concerning some work or business that you might be able to do together.