In other words, it is normal to deduct some insurance and taxes from wages. The company tells you that the salary is pre-tax salary, and the insurance is shared by individuals and companies, but the proportion shared by different companies is different.
In other words, if you want to cancel the contract, you should notify the company one month in advance, and if you want to cancel the contract with an individual, you should also notify it one month in advance, that's all.
Basically, if it's not too bad, you won't be dismissed after the probation period. Almost all companies have a probation period, which is normal, because if individuals feel inappropriate, they can choose other companies during this period without paying liquidated damages.