guitar tablature question for song, the imgur is a screen shot of it. do I hammer onto the 12 then pull off to the 8. or am i not even close?
The symbol pictured which is sometimes referred to as a slur in music notation (curved line that forms an arc connecting two notes) in the image is often used to denote a hammer on in tablature. A slide is usually indicated by a diagonal line / or \ depending if it's an ascending or descending slide.
But I don't see how you can be playing a note while fretting the string on the 5th fret and then hammer on to the 12th fret unless you execute the hammer on and pull off with your picking hand as Tim suggests in his answer. That is a more advanced technique that is not commonly used - so I can't discount the possibility that the tab author might be trying to indicate a slide from the 5th fret to the 12th fret and then back to the 8th fret.
If you can listen to a recording of the song, you should be able to determine if the guitarist in the recording is executing a slide or hammer on/pull off.
If that is not possible, you might try contacting the tab author and ask.