How do I access php variables declared in another section

Use a function in your theme’s functions.php to create these variables and then call the function in each template file as appropriate.

Thank you. Can you point me to any simple examples I can study to possibly get me further along?

I found a simple article here which helped.
https://www.themebig.com/94/create-wordpress-functions/

One question, how do variables work in relation to include and require?
If I include or require a file, are the variables of the included file accessible in the functions.php?

Assuming they are global variables, yes.

I have been experimenting some, and have learned some things but still have questions.

I have a variable declared in my head called $user and another called $user_profile. How do I save these variables in a function that I can call in a different section/template file?

Thanks (and sorry for so many questions)