Hi,
Can anyone help me determine the resolution (PPR) of this encoder?
[...]
What do they mean by "Current" and "Limit" in the PPR section in the upper right?
This is nothing much of a datasheet and it's full of errors

measuring time in µS, which means micro-Siemens (yeah, they probably meant µs) and leakage current in µV.
If they're so inept at making a proper datasheet for their products, I wouldn't trust the product to be reliable either.
The "current" and "limit" might refer to the number of poles that is possible with
current setup (or something like that) i.e. not electrical current but current as in "present". Limit may refer to the max. number of poles in this or that configuration and they seem to be based on the diameter of the motor housing.
Probably for some of the motors that they produce as well - they make motors in the range 8mmØ to 90mmØ (where "Ø" means diameter).
In your shoes, I'd strongly consider a product with a substantially higher amount of (correct) engineering data.