f-strings, also called “formatted string literals,” are string literals that have an f
at the beginning; and curly braces containing expressions that will be replaced with their values.
f-strings are evaluated at runtime.
So your code can be re-written as:
string1="go"
string2="now"
string3="great"
print(f"""
I will {string1} there
I will go {string2}
{string3}
""")
And this will evaluate to:
I will go there
I will go now
great
You can learn more about it here.