There are a few ways that you can open your Gmail inbox on your mobile device.
One way is to open the Gmail app. If you have the app installed on your device, you can tap the icon to open it.
Another way is to go to the Gmail website. If you type www.gmail.com into your mobile browser, you'll be able to access your inbox that way.
If you have a Google account, you can also use other Google apps to access your Gmail inbox. For example, the Google app allows you to see your Gmail messages along with other information from your account.
You can also use third-party apps to access your Gmail inbox. Some examples include Mailbox, myMail, and Inbox by Gmail. These apps are designed specifically for accessing and managing Gmail messages.