What is str()?

Answer 1

makes a string of everything inside the paranthesis.
for example:
str (7) = "7"

Answer 2

This is the function to turn the argument understood as a string (a text ou a non-mathematical element).

Answer 3

You can use it to make strings easier
For example:
a = "I"
b = "am"
print (a + b + str(19))