If you write this:

  #!/usr/bin/python
  import time
  time.sleep(5)
  fdafadsfadsf

It'll take 5 seconds to crash with a "NameError: name 'fdafadsfadsf' is not defined". Likewise, if you do this:

  #!/usr/bin/python
  import time
  x = 1
  time.sleep(5)
  print "x is "+x

It'll take 5 seconds to crash with "TypeError: cannot concatenate 'str' and 'int' objects"

In a language like Java, these would be syntax errors, and they'd be picked up at compile time as they're illegal in Java's syntax.

I assume they're legal in Python's syntax, because for all the syntax checker knows, time.sleep() might define fdafadsfadsf and convert x into a string. So they're runtime errors in Python.

Of course, Java still has runtime exceptions - null pointer exceptions, for example.