So I bought a new Pfluger spinning reel. As stated on the reel it only gives the # of yards of line up to 10# line. Does this mean I shouldn't put 12# mono line on it, or will it be fine most likely?

I wouldn't suggest going above 10# on a spinning reel if you're using mono and you'll probably be best off with 8. If you want to use stronger line you'll be much better off going with braid and adding a leader. 

Yo-Zuri Hybrid #6 has a breaking strength of 11.95 lbs.

 

5 hours ago, Bluebasser86 said:

I wouldn't suggest going above 10# on a spinning reel if you're using mono and you'll probably be best off with 8. If you want to use stronger line you'll be much better off going with braid and adding a leader. 

^^this right here

I think 10# is the max myself or some 8# Yo-Zuri ultra soft.

You're just asking for a headache. 

Spinning reels will be stamped with the 3 most common line sizes the maker assumes will be used on the reel. If you want to go with 12 that's fine, just know that with bigger diameter line the less of it the reel will hold. You can estimate how much line it will be by taking the 3 sizes and seeing how much it changes from the first to second and second to third. You only need an approximation as almost all reel brands have different diameters for the same size line. 

With all that being said, I would recommend against using 12lb test on a spinning reel unless it's braid in which case all those previous numbers can be thrown out anyway. 

For the most part I agree with all the above comments.  HOWEVER, I would also add that reel size matters as well as the line.  I use Sunline Super Natural 12lb mono on my 2500 size Stradics and very seldom ever have a problem.  Other lines I have used have been a real headache at 12lb, but the Sunline works well FOR ME.  YMMV.

Dave

I use 12 and 15 lb pline cx on 2 35 size pfluegers (a medalist and a patriarch) with no issues. The secret is forget the # test rating and be worried more about line diameter.