python f string literal

>>> name = "Eric"
>>> age = 74
>>> f"Hello, {name}. You are {age}."
'Hello, Eric. You are 74.'

#python3.6 is required
age = 12
name = "Simon"
print(f"Hi! My name is {name} and I am {age} years old")

# This answer might be long, but it explains more python f-strings, how to use them and when to use them.
# Python f-strings are used to write code faster.
# Here is an example:
name = "George"
age = 16
favorite_food = "pizza"

# Instead of doing this:
print("My name is", name, ", my age is", age, ", and my favorite food is", favorite_food)

# Or this:
print("My name is "+ name +", my age is "+ str(age)+ ", and my favorite food is "+ favorite_food)

# You could do this:
print(f"My name is {name}, my age is {age}, and my favorite food is {favorite_food}")

# You see that the code looks a little cleaner, and as you start using f-strings you realize you write much faster.
"""
Why put the f before the string, you ask?
Well if you didnt, the output would literally be {name} instead of the actual variable
One more thing: this is fairly new and only works with python 3.6 and higher.
"""

# do you remember str.format() stuff. 
# this is called F-string
# why F-string? because of the leading f character preceding the string literal
value = 'this one is cooler'
print(f"{value}") 

f-strings were added in python 3.6.
In older python versions, an f-string will result in a syntax error.
If you don't want to (or can't) upgrade, 
see How do I put a variable inside a String in Python?
for alternatives to f-strings.