Yes a days earning, at least 30.-, at most 3000.- per day, can be converted to equivalent time in jail* or equivalent time doing community work(4 hours community work = 1 day fine). at least 3 days, at most 180 days (more would mandate jail).

suspended means there's a trial period where the punishment isn't enforced and after which it can be fully or partially dropped if the guilty party didn't commit another crime.

And in this case it's 30 days worth of fine, how long the probation period lasts isn't specified. It's usually 2-5 years

*not going to figure out if jail or prison is the right term…

no, it means they are on a sort of probation for 30 days. if they cause trouble within that time, they will have to pay the fine on top of whatever new penalties they face.