Cloud Functions lets you run your code in a serviceable environment as a function. The service allocates the resources required for the function the be executed. When you increase the number of function calls, the service automatically scales and creates additional instances of your function.
A function is run in the runtime environment that corresponds to its programming language. Runtime environments are available for Node.js, Python, Go, PHP, and Bash.
Before writing your functions, review the programming model accepted in Cloud Functions.