A slide can be called using its individual URL. Please log in to the system so that you can access the slide, make sure you have the appropriate rights. You will get the individual URL when you open the slide, displayed directly in the URL bar.
But beware: The person who opens the link must have a valid access to presono, otherwise he can not see the slide of course.
Alternatively, you can of course create a presentation that only contains the one slide you want to share. You can then share this presentation as an individual link. You can find out more here: Share session; create presentation and share presentation