There is a problem in my hotspot connecting when trying to connect other device’s?

Start here, How to set up a Personal Hotspot on your iPhone or iPad - Apple Support and if needed, continue here, If Personal Hotspot is not working on your iPhone or iPad (Wi-Fi + Cellular) - Apple Support

What method, and what is not working? What if your friend trying to connect? If the Personal Hotspot is activated by your carrier, and you have turned it on, it should be visible to your friend. The second link I provided is troubleshooting steps. You will have to follow them, including the very last step of contacting Apple Support if necessary.