See https://orgmode.org/manual/Extracting-Source-Code.html

First set :tangle header args. This is the location which the file will be written.

:PROPERTIES:
:HEADER-ARGS: :tangle lit-test.el
:END:

Now, just by calling org-babel-tangle a file called lit-test.el is created with the following code blocks written to it separated by a couple newlines.

#+begin_src emacs-lisp
  (print "foo2")
#+end_src

#+begin_src emacs-lisp
  (print "bar2")
#+end_src