This is explained in the help document/overview/symbolic convention:
All units are unified by users in advance, such as: the unit of length is meters, the unit of force is kilonewtons, and so on.
-from the original words of the software administrator
For example, if you enter a numerical value, think about what unit it is in advance and make an agreement yourself. For example, your length can be considered as cm and the unit of force is Newton. If multiplied, the unit of the result is cm × Newton.
Does the vocational qualification certificate issued by the Central Audio-visual Education Center of the Ministry of Educa