For real?? Are they still using PR??
PR is a metric (a very important one) used by google to determine which page / URL is important. Google still uses PR, internally, but they've stopped making it public in 2016, which tells me that LTP hasn't been updated in 6 years lol...
Anyway, tools show PR 0 when the PR of a URL is indeed zero (ie. detected, but very low), but if they show PR N/A it means that the PR could be anywhere between 0 and 10 but the tool - for whatever reason - is unable to fetch the real PR, so it returns N/A... Either this, or the tool can fetch it but there's something wrong with the thing that makes the PR metric public.
In other words, if PR was still a thing (I mean, it still is a thing, but like I said, Google doesn't show us the real PR anymore) and you saw a page having PR 0 you would know for sure that THAT particular page is low quality because PR 0 means that the page either has no backlinks pointing back to it, or the backlinks are few, and / or low quality, and this tells google that pages with no / few / low quality links is not important, therefore its PR is 0.
But if you saw a page with PR N/A it could mean anything, it could mean that the page is not indexed yet, or even if it's indexed it could mean that it has no backlinks yet, or it can mean that the page does have backlinks (and the backlinks might be ultra awesome), but there could be technical issues with the tools that make the PR public.
But in all honesty, PR is a thing of the past, so even if you see a page with PR 10 it won't tell you anything of value, because that page might have had a PR 10 (which is the best score you can get in google's eyes for a page) in 2016 when the PR had been last actualized but since then the page could have been dropped to a PR 0 or even deindexed / penalized by google. So, don't stress with PR anymore...
