what does f' mean in python code example

Example 1: format specificer f strings python

#!/usr/bin/env python3

val = 12.3

print(f'{val:.2f}')
print(f'{val:.5f}')

Example 2: c="He is {} and he is {}".format(a,b) python

c="He is {} and he is {}".format(a,b) #add in bracket