Do you understand my meaning?

If there are advertisements, it would add 3 hours per week and depends on how many weeks you wish to run the ads.

Sehen Sie eine Übersetzung

Not quite.

If you are talking about cost, you would want to change it to, “If there are advertisements, it would cost an additional 3 hours per week. The overall cost would depend on how many weeks you wish to run the ads.” Since the ads are an option, it’s an additional expense to the customer. The overall time added to the project determines the overall cost and the overall cost depends on how long the ads are run.

If you are not talking about cost, then I don’t understand what you mean. However, I think just adding some more detail would help a lot!