I am unclear. A Possessed Shaman has Shared Skills.
At 1st level, a possessed shaman selects two skills. Both of these skills must use the same ability score. The possessed shaman treats these skills as if she had a number of ranks in them equal to her shaman level, and uses her Wisdom modifier in place of the ability modifier the skills would normally use. If either of the skills are class skills, she receives the usual +3 bonus on those skill checks for having ranks in those skills. These ranks do not stack with her other skill ranks (only the higher number of ranks applies).
This ability replaces spirit magic.
If I pick a skill like linguistics
Whenever you put a rank into this skill, you learn to speak and read a new language.
Does that mean that each Shaman level will get me a new language?
I would say yes, since it is as if you put a rank in the skill. Also, a strange scenario arises: you could also put ranks into Linguistics and get languages per rank there too, but only the higher of "real ranks" and "shaman-level pseudo ranks" would apply for skill bonuses.
i.e. a level 4 possessed shaman who chose linguistics as one of the shared skills who also put a point into linguistics every level would have 8 extra languages, but would only get Wis bonus + 4 + miscellaneous for skill rolls, not Wis bonus + 8 + miscellaneous.