Use cout to print variables: int age = 25; cout << age; displays 25. You need #include <iostream> at the top of your file for this to work. The << operator sends data to the output stream.
You can chain multiple << operators to print several things in one line of code. Add endl or "\n" to move to a new line: cout << "Age: " << age << endl; prints "Age: 25" and then starts a new line for the next output.