I'm guessing you are talking about Access.
If you are creating a one table/one function db then you might not need many forms, but if you are creating a database with more than 1 tables then you might need 1 for each table and a couple more for joining the tables and getting results.
The forms are there to help us and often to protect your data. You might need a form designed for data entry and a second one for read only queries and a third one for editing.
Also a second form could just be a subform, not intended to be used directly by the users but only as part of another form.