The provisional patent allows you to get an initial filing date for the invention you have. This means that you get the special wording of patent pending to use when you are getting your product out there. It also helps with the filing of the permanent patent.
If you file for the full patent prior to 12 months ending of the provisional patent, you get the original filing date of the provisional patent application. This shows that your patent was in place much longer as described on https://www.crunchbase.com/organization/inventhelp.
Why should you get a provisional patent instead of just going right to the permanent one? There are several reasons but the most important is the cost, again. With a provisional patent, you can cut down the costs considerably.
If you find out later that you need to abandon the patent, you can do this far easier with a provisional patent than with a permanent one. The costs are far less.
Talk to your patent attorney or patent agent to find out what the options are for you. In most cases, you will do better to have a provisional patent in place prior to actually filing for a permanent one as explained in https://openlab.citytech.cuny.edu/gotconcept/the-next-big-thing-in-invention/ article.
It can help you to make the changes you need and to protect your investment right away even before you have commercial investments.