Azure functions can be easily managed within the Azure Portal. Though there are certain restrictions, it allows managing the functions and executing them within the portal itself.
Once you navigate inside the function, you can see all available functions within that function app. All the functions I have in the above screen are Http Triggers.
Once you click on the 'Run' button, You will be prompted to enter the HTTP request information such as headers, query string and the request body.
Once you execute, the Output window will show up the execution output with HTTP status.
Now you might argue that this can be done using an HTTP simulator like Postman as well. Yes it is possible for HTTP Triggers, but from the portal you can execute other Azure Functions such as Timer Triggers as well.
The console right below will show up the execution log.
For each function you get Manage and Monitor tabs. With Manage tab you can easily disable or enable the functions.
With the Monitor tab you can configure Application Insights to log the execution logs and read through them.