The wellness allowance is a way for employers to subsidize employees' wellness activities. The contribution is tax-free for the employee and deductible for the employer.
There are some rules and regulations regarding what is eligible for health care and what is not. Among other things, activities and treatments that cost more than SEK 1,000 per occasion may not be paid for with the wellness allowance, however, this does not apply if the activity contains elements of exercise.
Read more about tax-free health care on the Swedish Tax Agency's website.