dumps takes an object and produces a string:
>>> a = {'foo': 3}
>>> json.dumps(a)
'{"foo": 3}'
load would take a file-like object, read the data from that object, and use that string to create an object:
with open('file.json') as fh:
a = json.load(fh)
Note that dump and load convert between files and objects, while dumps and loads convert between strings and objects. You can think of the s-less functions as wrappers around the s functions:
def dump(obj, fh):
fh.write(dumps(obj))
def load(fh):
return loads(fh.read())