And go beyond "it changes your ability" because that is honestly as vague as you can get. With that statement, I might just think it changes my ability to No Guard.
It seems like it switches between the non-hidden abilities. For example if you have a Lucario with Steadfast you could switch it to Inner Focus. Again it will not switch abilities to hidden abilities so you couldnt get a Solar Power Chairzard with this method. According to the link I read its a useable item thats in your medicine pouch. So you would use it like a Thunderstone and then it will go away.
When used on a Pokémon, this item will change its ability to the other standard ability it can have. If a Pokémon only has one ability, it will not work. It will not change a Pokémon with its Hidden Ability or change a Pokémon to have its Hidden Ability