Gmail on Mail app does not show notifications

Hello, Francisco_Fernandez1, what you can do to troubleshoot this is I want you to go into Settings > Notifications > Scroll down to Gmail, then click on it and see if the allow notifications button is turned on or not. Then see if Badges and Sounds are turned on. If they all are already turned on make sure you do not have DND (Do Not Disturb) on, to check that go into your control center by swiping down from the top right-hand corner to the bottom left-hand corner, or if you have an older iPhone swipe up from the bottom. Once, you are in the control center see if there is a moon-shaped icon that is turned on. If none of those work then make sure your Gmail notifications I showed you how to get to are on and then restart your iPhone. You can restart your iPhone by holding down the Power button / Side button and the volume buttons at the same time until the slide to power off screen comes and then just slide to power off. If you have an older iPhone hold the home button and the power button / side button until the slide to power off screen comes on and then slide to power off. To power back on your iPhone just hold the Power / Side button and wait for the apple logo and then you can let go and let it turn on. Let me know if you have any other questions. :)