I have a start and end date of a timeline, I wanted to count the weekends in case the end date would be 11/11/2018, how to use the function:
=DIATRABALHO(C24;E24;Tabela1[DATA])
To count on the weekends?
Would it also be possible to add additional holidays? In addition to the required? 
You can use the function:
=DIATRABALHO.INTL(data inicial; dias;[fimdesemana], [feriados])
At the weekend, you can tell what you consider this weekend. Whether it's Saturday or Sunday (1) or other options.
Excel, in newer versions, will display the options that you can report on [weekend]. Use the same formula, but using the weekend parameter.
=DIATRABALHO.INTL(C24;E24;1;Tabela1[DATA])
Notice the number 1 in the above function.
However, in your case, you can ignore the options you have there and use it like this:
=DIATRABALHO.INTL(C24;E24;"0000000";Tabela1[DATA])
If the answer is giving an extra day, do this: subtract -1.
=DIATRABALHO.INTL(C24;E24;"0000000";Tabela1[DATA])-1