12Mis the current gas block limit
13.2sis the average block time
// Specifies that the source code is for a version of Solidity of exactly 0.7.0
pragma solidity 0.7.0;

// A contract is a collection of functions and data (its state)
// that resides at a specific address on the Ethereum blockchain.
contract HelloWorld {

    // The keyword "public" makes variables accessible from outside a contract
    // and creates a function that other contracts or SDKs can call to access the value
    string public message;

    // A special function only run during the creation of the contract
    constructor(string memory initMessage) public {
        // Takes a string value and stores the value in the memory data storage area,
        // setting `message` to that value
        message = initMessage;
    }

    // A publicly accessible function that takes a string as a parameter
    // and updates `message`
    function update(string memory newMessage) public {
        message = newMessage;
    }
}

from ethereum.org