You can't do this using table data entry. You shouldn't enter data directly into tables anyway.
If you create a form you can use vba code to to set the valu in the Scheduled Cleaning field, assuming you have the other two values.
However, I'm not sure how you get it to recognise what you have entered in the Frequency field.
If you want to add a specific number of months, then you should set the datatype of the Frequency field to be a number and make it clear on the form that the user should enter a number of months.
