You don't. Jira's permissions are permissive, not restrictive.
To do this, you need to remove whatever it is that is giving your user access to the projects you don't want them to see, and then grant them the permission to see that one project. Take a look at how the "JIRA users" group is being used - you'll need to unpick that if you've still got the defaults.
I’m a designer on the Jira team. For a long time, I’ve fielded questions from other designers about how they should be using Jira Software with their design team. I’ve also heard feedback from other ...
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