A Federal trademark grants you important rights in the United States to use and defend your name, for the goods or services you have described. Trademark registration gives you an exclusive right to use the name in your area of business. This is a very valuable right.
Having a registered trademark means that if others attempt to use your name for similar or identical goods, or a name that is similar to your name for similar or identical goods, you have legal remedies to object to their use and stop them.
And once your trademark is granted, you have the right to use the valuable circle-R symbol, indicating that your name is registered. This is a big "keep away" sign to potential infringers who are thinking of using the identical or a similar name for similar goods or services. They will know that you are together enough to have gone through the registration process, and are likely to aggressively defend your rights against them.
But trademark registration is slow and not cheap, with filing fees per name and per trademark class, and often the need to hire an attorney. And some names are not expected to last long enough to get through a trademark process, for example if your name is for an event, or a seasonal product. In these cases, filing a Federal trademark application is probably not a good use of resources.