How to use uBlock Origin to block just the page stackexchange.com without blocking the entire stackexchange network?

Solution 1:

This answer attempts to block Hot Network Questions (HNQ) only on Stack Exchange (SE) homepage (as per OP's comment).

The HNQ on SE Homepage is inside a div with the ID question-list thus the needed filter is stackexchange.com###question-list.

This filter will only block HNQ on the SE homepage. It won't block SE Realtime Questions (the parent container is main-area which is shared with an HNQ list). Neither will any question lists on any of their other sites block them. SE uses a div with the ID question-mini-list on their homepage and the ID questions on their Questions lists.