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 which people can consider or discuss to decide whether it is true.

In the United States, a proposition is a question or statement about an issue of public policy which 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.

If someone who you do not know very well propositions you, they suggest that you have sex with them.