Based solely on the quote you posted, it sounds like they are just giving you a 6% "bonus" at the end of the year instead of a 401(k) match. Maybe they intended to set up a 401(k) plan but decided not to for whatever reason.
The fact they take taxes out ("you will receive a net amount") strongly indicates that this is just cash compensation and has no ties to any tax-advantaged retirement plan. You would be responsible for putting the cash into a retirement plan, subject to the contribution limits applicable to you. You would then receive a tax deduction at the end of the year.
Or you could spend it on whatever you want - I see nothing that requires you to put it towards retirement.
Trying to figure out if this arrangement is actually better or worse than having a 401k offered.
If you want to contribute to retirement above the IRA limits, then this is a bad deal*. It would not be considered a "401(k) contribution" and you would be subject to whatever limits apply to you.
Another option would be to contribute it to a Roth IRA, which has future tax benefits, meaning if your tax rate is higher when you withdraw from it you'll pay less tax then if you had contributed more to a tax-deferred IRA today.
Or take advantage of other tax-deferred accounts like an HSA or ESA.
The main point is that this 6% is like any other income - any tax planning you want to to with it is the same as if it were part of your salary.
There is a lot of speculation based on very little information; I would ask these questions of your benefits/HR department and see if they give more information.
* To be fair, it's not as good as if they had actually set up a 401(k), but it's effectively a 6% bonus so it's still a benefit to you.