For a Work resource, you need to set the name and type. If you don’t know exactly how many such work resources will be needed in the project, leave the Max. Units field equal to 100%. The value of this field can be clarified later.
In case you know the number of specialists or equipment with this name, you can indicate this number in the Max. Units field - for example, for 5 identical specialists, you will set the Max. Units field to 500%.